[U-Boot] [PATCH 07/10] clk: imx8: add i.MX8QM clk driver

[Peng Fan]

> -----Original Message-----
> From: Fabio Estevam [mailto:festevam at gmail.com]
> Sent: 2019年1月28日 22:24
> To: Stefano Babic <sbabic at denx.de>
> Cc: Peng Fan <peng.fan at nxp.com>; Fabio Estevam
> <fabio.estevam at nxp.com>; u-boot at lists.denx.de; dl-uboot-imx
> <uboot-imx at nxp.com>; Lukasz Majewski <lukma at denx.de>
> Subject: Re: [U-Boot] [PATCH 07/10] clk: imx8: add i.MX8QM clk driver
> 
> Hi Stefano,
> 
> On Mon, Jan 28, 2019 at 12:04 PM Stefano Babic <sbabic at denx.de> wrote:
> 
> > Ok - I see you decide to split the code on depend of the SOC type.
> > Nevertheless, even if defines are different, it seems to me that there
> > is still a lot of common code (_imx8_clk_enable is very similar). Do
> > we need really a separate file for each MX8 variant ? Which are the
> > blocking points that avoid to do this ? I am looking at the patch, but
> > I do not find such as issue. Can you explain it ?
> 
> I am also concerned about the current i.MX clock driver status in U-Boot and I
> expressed this during my review of Lukasz's patch that added a imx6 clock
> driver.
> 
> It does not scale well as we can see by the huge switch statement in this
> patch. Of course this would need to grow when new peripherals clocks are
> added.
> 
> I think a better approach would be to use the same scheme as done in the
> kernel with common clock framework.
> 
> Barebox folows this same approach. For example:
> 
> i.MX8M clock driver:
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.p
> engutronix.de%2Fcgit%2Fbarebox%2Ftree%2Fdrivers%2Fclk%2Fimx%2Fclk-i
> mx8mq.c&data=02%7C01%7Cpeng.fan%40nxp.com%7C124a7ae228794
> 2551ea208d6852c3c0a%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C
> 0%7C636842822364000869&sdata=6xwmlVrr2MGKkRCNUFZTBcec9KP
> RNoID%2FBWTU5HFKcg%3D&reserved=0
> 
> i.MX6Q clock driver:
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.p
> engutronix.de%2Fcgit%2Fbarebox%2Ftree%2Fdrivers%2Fclk%2Fimx%2Fclk-i
> mx6.c&data=02%7C01%7Cpeng.fan%40nxp.com%7C124a7ae22879425
> 51ea208d6852c3c0a%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%
> 7C636842822364000869&sdata=m6%2FRa8HY9M1aPXy45%2Bp0aa9Xit
> 6cMUVqBw%2F4UVTSOz0%3D&reserved=0
> 
> It allows syncing with the kernel clock driver more easily and it makes it
> easier to maintain several i.MX SoCs in the long term.

I thought about this before, but this will increase SPL code side a lot when
SPL DM clk used.

Regards,
Peng.