[U-Boot] [PATCH v2 00/10] clk: imx: Add i.MX6 CLK support
Peng Fan
peng.fan at nxp.com
Tue Apr 23 09:11:21 UTC 2019
> -----Original Message-----
> From: Lukasz Majewski [mailto:lukma at denx.de]
> Sent: 2019年4月23日 16:46
> To: Peng Fan <peng.fan at nxp.com>
> Cc: Jagan Teki <jagan at amarulasolutions.com>; Stefano Babic
> <sbabic at denx.de>; Fabio Estevam <fabio.estevam at nxp.com>; Simon Glass
> <sjg at chromium.org>; Tom Rini <trini at konsulko.com>; Marek Vasut
> <marek.vasut+renesas at gmail.com>; Neil Armstrong
> <narmstrong at baylibre.com>; Philipp Tomsich
> <philipp.tomsich at theobroma-systems.com>; Maxime Ripard
> <maxime.ripard at bootlin.com>; Michael Trimarchi
> <michael at amarulasolutions.com>; Andre Przywara
> <andre.przywara at arm.com>; U-Boot-Denx <u-boot at lists.denx.de>;
> linux-amarula at amarulasolutions.com; dl-uboot-imx <uboot-imx at nxp.com>
> Subject: Re: [U-Boot] [PATCH v2 00/10] clk: imx: Add i.MX6 CLK support
>
> On Tue, 23 Apr 2019 07:47:38 +0000
> Peng Fan <peng.fan at nxp.com> wrote:
>
> > Hi Lukasz,
> >
> > > -----Original Message-----
> > > From: Lukasz Majewski [mailto:lukma at denx.de]
> > > Sent: 2019年4月20日 6:18
> > > To: Peng Fan <peng.fan at nxp.com>
> > > Cc: Jagan Teki <jagan at amarulasolutions.com>; Stefano Babic
> > > <sbabic at denx.de>; Fabio Estevam <fabio.estevam at nxp.com>; Simon
> Glass
> > > <sjg at chromium.org>; Tom Rini <trini at konsulko.com>; Marek Vasut
> > > <marek.vasut+renesas at gmail.com>; Neil Armstrong
> > > <narmstrong at baylibre.com>; Philipp Tomsich
> > > <philipp.tomsich at theobroma-systems.com>; Maxime Ripard
> > > <maxime.ripard at bootlin.com>; Michael Trimarchi
> > > <michael at amarulasolutions.com>; Andre Przywara
> > > <andre.przywara at arm.com>; U-Boot-Denx <u-boot at lists.denx.de>;
> > > linux-amarula at amarulasolutions.com; dl-uboot-imx
> <uboot-imx at nxp.com>
> > > Subject: Re: [U-Boot] [PATCH v2 00/10] clk: imx: Add i.MX6 CLK
> > > support
> > >
> > > On Fri, 19 Apr 2019 08:52:28 +0000
> > > Peng Fan <peng.fan at nxp.com> wrote:
> > >
> > > > > On Fri, 19 Apr 2019 11:56:25 +0530 Jagan Teki
> > > > > <jagan at amarulasolutions.com> wrote:
> > > > >
> > > > > > On Fri, Apr 5, 2019 at 2:20 AM Lukasz Majewski <lukma at denx.de>
> > > > > > wrote:
> > > > > > >
> > > > > > > Hi Jagan,
> > > > > > >
> > > > > > > > On Thu, Apr 4, 2019 at 3:31 PM Lukasz Majewski
> > > > > > > > <lukma at denx.de> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, 4 Apr 2019 14:56:36 +0530 Jagan Teki
> > > > > > > > > <jagan at amarulasolutions.com> wrote:
> > > > > > > > >
> > > > > > > > > > On Thu, Apr 4, 2019 at 2:31 PM Lukasz Majewski
> > > > > > > > > > <lukma at denx.de> wrote:
> > > > > > > > > > >
> > > > > > > > > > > On Tue, 2 Apr 2019 16:58:33 +0530 Jagan Teki
> > > > > > > > > > > <jagan at amarulasolutions.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > > This is revised version of previous i.MX6 clock
> > > > > > > > > > > > management [1].
> > > > > > > > > > > >
> > > > > > > > > > > > The main difference between previous version is
> > > > > > > > > > > > - Group the i.MX6 ccm clocks into gates and tree
> > > > > > > > > > > > instead of handling the clocks in simple way using
> > > > > > > > > > > > case statement.
> > > > > > > > > > > > - use gate clocks for enable/disable management.
> > > > > > > > > > > > - use tree clocks for get/set rate or parent
> > > > > > > > > > > > traverse management.
> > > > > > > > > > > > - parent clock handling via clock type.
> > > > > > > > > > > > - traverse the parent clock using recursive
> > > > > > > > > > > > functionlaity.
> > > > > > > > > > > >
> > > > > > > > > > > > The main motive behind this tree framework is to
> > > > > > > > > > > > make the clock tree management simple and useful
> > > > > > > > > > > > for U-Boot requirements instead of garbing Linux
> > > > > > > > > > > > clock management code.
> > > > > > > > > > > >
> > > > > > > > > > > > We are trying to manage the Allwinner clocks with
> > > > > > > > > > > > similar kind, so having this would really help
> > > > > > > > > > > > i.MX6 as well.
> > > > > > > > > > > >
> > > > > > > > > > > > Added simple names for clock macros, but will
> > > > > > > > > > > > update it in future version.
> > > > > > > > > > > >
> > > > > > > > > > > > I have skipped ENET clocks from previous series,
> > > > > > > > > > > > will add it in future patches.
> > > > > > > > > > > >
> > > > > > > > > > > > Changes for v2:
> > > > > > > > > > > > - changed framework patches.
> > > > > > > > > > > > - add support for imx6qdl and imx6ul boards
> > > > > > > > > > > > - add clock gates, tree.
> > > > > > > > > > > >
> > > > > > > > > > > > [1] https://patchwork.ozlabs.org/cover/950964/
> > > > > > > > > > > >
> > > > > > > > > > > > Any inputs?
> > > > > > > > > > >
> > > > > > > > > > > Hmm.... It looks like we are doing some development
> > > > > > > > > > > in parallel.
> > > > > > > > > > >
> > > > > > > > > > > Please look into following commit [1]:
> > > > > > > > > > > https://patchwork.ozlabs.org/patch/1034051/
> > > > > > > > > > >
> > > > > > > > > > > It ports from Linux 5.0 the CCF framework for iMX6Q,
> > > > > > > > > > > which IMHO in the long term is a better approach.
> > > > > > > > > > > The code is kept simple and resembles the code from
> > > > > > > > > > > Barebox.
> > > > > > > > > > >
> > > > > > > > > > > Please correct me if I'm wrong, but the code from
> > > > > > > > > > > your work is not modeling muxes, gates and other
> > > > > > > > > > > components from Linux CCF.
> > > > > > > > > >
> > > > > > > > > > The U-Boot implementation of CLK would require as
> > > > > > > > > > minimal and simple as possible due to requirement of
> > > > > > > > > > U-Boot itself. Hope you agree this point?
> > > > > > > > >
> > > > > > > > > Now i.MX6 is using clock.c CLK implementation. If we
> > > > > > > > > decide to replace it - we shall do it in a way, which
> > > > > > > > > would allow us to follow Linux kernel. (the barebox
> > > > > > > > > implementation is a stripped CCF from Linux, the same is
> > > > > > > > > in patch [1]).
> > > > > > > > > > if yes having CCF stack code to handle all clock with
> > > > > > > > > > respective separate drivers management is may not
> > > > > > > > > > require as of now, IMHO.
> > > > > > > > >
> > > > > > > > > I do have a gut feeling, that we will end up with the
> > > > > > > > > need to have the CCF framework ported anyway. As for
> > > > > > > > > example imx7/8 can re-use muxes, gates code.
> > > > > > > >
> > > > > > > > As per my experience the main the over-ahead to handle
> > > > > > > > clocks in U-Boot if we go with separate clock drivers is
> > > > > > > > for Video and Ethernet peripherals. these are key IP's
> > > > > > > > which use more clocks from U-Boot point-of-view, others
> > > > > > > > can be handle pretty straight-forward unless if they don't
> > > > > > > > have too much tree chain.
> > > > > > > >
> > > > > > > > On this series, the tree management is already supported
> > > > > > > > ENET in i.MX6, and Allwinner platforms.
> > > > > > > >
> > > > > > > > As of now, I'm thinking I can handle reset of the clocks
> > > > > > > > with similar way.
> > > > > > >
> > > > > > > But this code also supports ENET and ESDHCI clocks on i.MX6Q
> > > > > > > (as supporting those was the motivator for this work).
> > > > > > >
> > > > > > > One important thing to be aware of - the problem with SPL's
> > > > > > > footprint. The implementation with clock.c is small and
> > > > > > > simple, but doesn't scale well.
> > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > > However, those are only my "feelings" after a glimpse
> > > > > > > > > look
> > > > > > > > > - I will look into your code more thoroughly and provide
> > > > > > > > > feedback.
> > > > > > > >
> > > > > > > > Please have a look, if possible check even the code size
> > > > > > > > by adding USDHC clocks.
> > > > > > >
> > > > > > > Yes, code size (especially in SPL) is an _important_ factor
> > > > > > > here.
> > > > > > > >
> > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > This series is using recursive calls for handling
> > > > > > > > > > parenting stuff to handle get or set rates, which is
> > > > > > > > > > fine for handling clock tree management as far as
> > > > > > > > > > U-Boot point-of-view. We have faced similar situation
> > > > > > > > > > as I explained in commit message about Allwinner
> > > > > > > > > > clocks [2] and we ended up going this way.
> > > > > > > > >
> > > > > > > > > I'm not Allwinner expert - but if I may ask - how far
> > > > > > > > > away is this implementation from mainline Linux kernel?
> > > > > > > > >
> > > > > > > > > How difficult is it to port the new code (or update it)?
> > > > > > > >
> > > > > > > > Allwinner clocks also has similar gates, muxs, and with
> > > > > > > > other platform stuff which has too much scope in Linux to
> > > > > > > > use CCM.
> > > > > > >
> > > > > > > For example the barebox managed to get subset of Linux CCF
> > > > > > > ported, without loosing the CCF similarity.
> > > > > > >
> > > > > > >
> > > > > > > Important factors/requirements for the i.MX clock code:
> > > > > > >
> > > > > > > 1. Easy maintenance in long-term
> > > > > > >
> > > > > > > 2. Reusing the code in SPL (with a very important factor of
> > > > > > > _code_size_).
> > > > > > >
> > > > > > > 3. Reuse the code for other i.MX SoCs (imx7, imx8)
> > > > > > >
> > > > > > > 4. Effort needed to use DM with this code
> > > > > >
> > > > > > I understand your points, I was managed this series based on
> > > > > > these requirements as well.
> > > > >
> > > > > Ok.
> > > > >
> > > > > Could you share the delta of footprint size (u-boot.img/SPL)
> > > > > with and without your patch (on imx6q) ?
> > > > >
> > > > > In my case the CCF caused increase of u-boot.img proper (as it
> > > > > was not yet adapted to SPL):
> > > > >
> > > > > 415KiB -> 421KiB = 6KiB increase of size (< 2%).
> > > > >
> > > > > (This can be further reduced by using OF_PLATDATA).
> > > > >
> > > > > This CCF code hasn't been ported to SPL (yet)
> > > > >
> > > > > > We even consider the foot-print, atleast for recursive calls
> > > > > > of handling parenting scale well.
> > > > >
> > > > > With CCF porting v3 I'm going to provide some caching, so the
> > > > > descending would be done at most once.
> > > > >
> > > > > > May be we can
> > > > > > consider to design based on this as per U-Boot.
> > > > > >
> > > > >
> > > > > Please look into point 1. Having code ported from Linux is IMHO
> > > > > better in the long term.
> > > >
> > > > Agree.
> > > >
> > > > >
> > > > > > Let me come-back with another series or do you have any inputs
> > > > > > or questions, please post it.
> > > > >
> > > > > I will post CCF port for imx6q v3 in a few days.
> > > >
> > > > Looking forward your new patchset.
> > > > Working on enabling i.MX8MM CCF support.
> > >
> > > Output of 'dm tree' on imx6q:
> > >
> > > clk 1 [ ] fixed_rate_clock |-- ckil
> > > clk 2 [ ] fixed_rate_clock |-- ckih1
> > > clk 3 [ + ] fixed_rate_clock `-- osc
> > > clk 4 [ + ] imx_clk_pllv3 |-- pll2_bus
> > > clk 7 [ ] imx_clk_pfd | |--
> > > pll2_pfd0_352m
> > > clk 8 [ + ] imx_clk_pfd | `--
> > > pll2_pfd2_396m
> > > clk 9 [ + ] imx_clk_mux | |--
> > > usdhc1_sel
> > > clk 13 [ + ] imx_clk_divider | |
> `--
> > > usdhc1_podf
> > > clk 22 [ ] imx_clk_gate2 | |
> > > `-- usdhc1
> > > clk 10 [ + ] imx_clk_mux | |--
> > > usdhc2_sel
> > > clk 14 [ + ] imx_clk_divider | |
> `--
> > > usdhc2_podf
> > > clk 23 [ ] imx_clk_gate2 | |
> > > `-- usdhc2
> > > clk 11 [ + ] imx_clk_mux | |--
> > > usdhc3_sel
> > > clk 15 [ + ] imx_clk_divider | |
> `--
> > > usdhc3_podf
> > > clk 24 [ ] imx_clk_gate2 | |
> > > `-- usdhc3
> > > clk 12 [ + ] imx_clk_mux | `--
> > > usdhc4_sel
> > > clk 16 [ + ] imx_clk_divider |
> `--
> > > usdhc4_podf
> > > clk 25 [ ] imx_clk_gate2 |
> > > `-- usdhc4
> > > clk 5 [ + ] imx_clk_pllv3 `-- pll3_usb_otg
> > > clk 6 [ + ] imx_clk_fixed_factor `-- pll3_60m
> > > clk 17 [ + ] imx_clk_divider `--
> > > ecspi_root
> > > clk 18 [ ] imx_clk_gate2
> |--
> > > ecspi1
> > > clk 19 [ ] imx_clk_gate2
> |--
> > > ecspi2
> > > clk 20 [ ] imx_clk_gate2
> |--
> > > ecspi3
> > > clk 21 [ ] imx_clk_gate2
> `--
> > > ecspi4
> > >
> >
> > Do you have a public tree/branch for CCF?
>
> Please find the CCF devel work:
> https://github.com/lmajewski/u-boot-dfu/commits/CCF-devel
>
> The CCF starts from: c792297e1a47ead02ff2baa4f162de8782b29910
Thanks.
>
> (below you will find imx6q DM/DTS conversion code).
>
> What is added when compared to the original one:
>
> - SPL support
>
> - Some fixes for v2019.04+
>
> What is on the TO DO list:
>
> - OF_PLATDATA for SPL (as I did not used any optimisations yet).
>
>
> >I am adding imx8mm clk and
> > would like to base on your tree. I think need to extend clk_ops to
> >support mux/divider, but not just get rate.
>
> Some mux/divider is provided (clk-mux.c / clk-divider.c)
After reading into details, there is no clk core logic.
mux not support reparenting.
Divider not support rate setting.
no composite clk support.
We could not directly reuse Linux vendor clk driver, need adapt to U-Boot,
should not be hard from your code.
When multiple devices sources from one PLL, one device might would
like to set pll value that break other devices, there is no logic to protect
if support freq changing.
Do you have plan work on the upper items?
i.MX8MM use composite heavily in Linux, so I have started.
Thanks,
Peng.
>
> > To avoid conflict with
> > you work, if you have a public tree, that could be good.
>
> No problem. Thanks for the interest.
>
> >
> > Thanks,
> > Peng.
> >
> >
> > >
> > >
> > > >
> > > > Regards,
> > > > Peng.
> > > >
> > > > >
> > > > > >
> > > > > > Jagan.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Lukasz Majewski
> > > > >
> > > > > --
> > > > >
> > > > > DENX Software Engineering GmbH, Managing Director:
> Wolfgang
> > > > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194
> > > > > Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax:
> > > > > (+49)-8142-66989-80 Email: lukma at denx.de
> > >
> > >
> > >
> > >
> > > Best regards,
> > >
> > > Lukasz Majewski
> > >
> > > --
> > >
> > > DENX Software Engineering GmbH, Managing Director: Wolfgang
> > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > > lukma at denx.de
>
>
>
>
> Best regards,
>
> Lukasz Majewski
>
> --
>
> DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> lukma at denx.de
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