[PATCH v1 1/1] usb: host: tegra: implement dts based xcvr setup
Svyatoslav Ryhel
clamor95 at gmail.com
Wed Aug 23 13:28:38 CEST 2023
23 серпня 2023 р. 13:49:18 GMT+03:00, Thierry Reding <thierry.reding at gmail.com> написав(-ла):
>On Sun, Aug 20, 2023 at 09:10:17PM +0200, Marek Vasut wrote:
>> On 8/20/23 20:32, Svyatoslav Ryhel wrote:
>> > 20 серпня 2023 р. 21:14:15 GMT+03:00, Marek Vasut <marex at denx.de> написав(-ла):
>> > > On 8/20/23 09:13, Svyatoslav Ryhel wrote:
>> > > > 20 серпня 2023 р. 05:23:14 GMT+03:00, Marek Vasut <marex at denx.de> написав(-ла):
>> > > > > On 8/19/23 17:06, Svyatoslav Ryhel wrote:
>> > > > > > Some devices (like ASUS TF201) may not have fuse based xcvr setup
>> > > > > > which will result in not working USB line. To fix this situation
>> > > > > > allow xcvr setup to be performed from device tree values if
>> > > > > > nvidia,xcvr-setup-use-fuses is not defined.
>> > > > > >
>> > > > > > Tested-by: Svyatoslav Ryhel <clamor95 at gmail.com> # ASUS TF201
>> > > > >
>> > > > > I would hope so. Usually T-B tags are not added by the patch author, but that's a detail, and here it has the added model value, so keep it.
>> > > > >
>> > > > > > Signed-off-by: Svyatoslav Ryhel <clamor95 at gmail.com>
>> > > > > > ---
>> > > > > > drivers/usb/host/ehci-tegra.c | 53 +++++++++++++++++++++++++++++++----
>> > > > > > 1 file changed, 48 insertions(+), 5 deletions(-)
>> > > > > >
>> > > > > > diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
>> > > > > > index 2cf1625670..f24baf8f0c 100644
>> > > > > > --- a/drivers/usb/host/ehci-tegra.c
>> > > > > > +++ b/drivers/usb/host/ehci-tegra.c
>> > > > > > @@ -81,6 +81,8 @@ struct fdt_usb {
>> > > > > > enum periph_id periph_id;/* peripheral id */
>> > > > > > struct gpio_desc vbus_gpio; /* GPIO for vbus enable */
>> > > > > > struct gpio_desc phy_reset_gpio; /* GPIO to reset ULPI phy */
>> > > > > > + bool xcvr_setup_use_fuses; /* Indicates that the value is read from the on-chip fuses */
>> > > > > > + u32 xcvr_setup; /* Input of XCVR cell, HS driver output control */
>> > > > > > };
>> > > > > > /*
>> > > > > > @@ -464,10 +466,21 @@ static int init_utmi_usb_controller(struct fdt_usb *config,
>> > > > > > /* Recommended PHY settings for EYE diagram */
>> > > > > > val = readl(&usbctlr->utmip_xcvr_cfg0);
>> > > > > > - clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MASK,
>> > > > > > - 0x4 << UTMIP_XCVR_SETUP_SHIFT);
>> > > > > > - clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MSB_MASK,
>> > > > > > - 0x3 << UTMIP_XCVR_SETUP_MSB_SHIFT);
>> > > > > > +
>> > > > > > + if (!config->xcvr_setup_use_fuses) {
>> > > > > > + clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MASK,
>> > > > > > + config->xcvr_setup <<
>> > > > > > + UTMIP_XCVR_SETUP_SHIFT);
>> > > > > > + clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MSB_MASK,
>> > > > > > + config->xcvr_setup <<
>> > > > > > + UTMIP_XCVR_SETUP_MSB_SHIFT);
>> > > > > > + } else {
>> > > > > > + clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MASK,
>> > > > > > + 0x4 << UTMIP_XCVR_SETUP_SHIFT);
>> > > > >
>> > > > > What is this hard-coded value ?
>> > > > >
>> > > >
>> > > > 0x4 and 0x3 (not same) but those are not in the device tree. Mainline linux
>> > > > driver seems not set this at all if use_fuses is enabled but I decided to keep
>> > > > original setup just to not cause regressions.
>> > > >
>> > > > https://github.com/clamor-s/linux/blob/transformer/drivers/usb/phy/phy-tegra-usb.c#L587-L590
>> > > >
>> > > > > Why not place this value into config->xcvr_setup in e.g. probe() and drop this if/else statement ?
>> > > > >
>> > > >
>> > > > Because config->xcvr_setup should matter only if use_fuses is disabled
>> > >
>> > > Can it matter always instead ?
>> > >
>> >
>> > No, it cannot. You are inversing hw design. Xcvr_setup matters only if use_fuses is disabled. If use_fuses is on (which is default state) xcvr values are taken from chip fuse.
>>
>> The way I read this block of code is, some value is written into the
>> register if config->xcvr_setup_use_fuses is false, another value if
>> config->xcvr_setup_use_fuses is true . Why not do this determination once in
>> probe and then just program the appropriate value instead ?
>>
>> > > > > > + clrsetbits_le32(&val, UTMIP_XCVR_SETUP_MSB_MASK,
>> > > > > > + 0x3 << UTMIP_XCVR_SETUP_MSB_SHIFT);
>> > > > > > + }
>> > > > > > +
>> > > > > > clrsetbits_le32(&val, UTMIP_XCVR_HSSLEW_MSB_MASK,
>> > > > > > 0x8 << UTMIP_XCVR_HSSLEW_MSB_SHIFT);
>> > > > > > writel(val, &usbctlr->utmip_xcvr_cfg0);
>> > > > > > @@ -522,7 +535,9 @@ static int init_utmi_usb_controller(struct fdt_usb *config,
>> > > > > > setbits_le32(&usbctlr->utmip_bat_chrg_cfg0, UTMIP_PD_CHRG);
>> > > > > > clrbits_le32(&usbctlr->utmip_xcvr_cfg0, UTMIP_XCVR_LSBIAS_SE);
>> > > > > > - setbits_le32(&usbctlr->utmip_spare_cfg0, FUSE_SETUP_SEL);
>> > > > > > +
>> > > > > > + if (config->xcvr_setup_use_fuses)
>> > > > > > + setbits_le32(&usbctlr->utmip_spare_cfg0, FUSE_SETUP_SEL);
>> > > > > > /*
>> > > > > > * Configure the UTMIP_IDLE_WAIT and UTMIP_ELASTIC_LIMIT
>> > > > > > @@ -843,6 +858,8 @@ static const struct ehci_ops tegra_ehci_ops = {
>> > > > > > static int ehci_usb_of_to_plat(struct udevice *dev)
>> > > > > > {
>> > > > > > struct fdt_usb *priv = dev_get_priv(dev);
>> > > > > > + u32 usb_phy_phandle;
>> > > > > > + ofnode usb_phy_node;
>> > > > > > int ret;
>> > > > > > ret = fdt_decode_usb(dev, priv);
>> > > > > > @@ -851,6 +868,32 @@ static int ehci_usb_of_to_plat(struct udevice *dev)
>> > > > > > priv->type = dev_get_driver_data(dev);
>> > > > > > + ret = ofnode_read_u32(dev_ofnode(dev), "nvidia,phy", &usb_phy_phandle);
>> > > > > > + if (ret) {
>> > > > > > + log_debug("%s: required usb phy node isn't provided\n", __func__);
>> > > > > > + priv->xcvr_setup_use_fuses = true;
>> > > > > > + return 0;
>> > > > > > + }
>> > > > > > +
>> > > > > > + usb_phy_node = ofnode_get_by_phandle(usb_phy_phandle);
>> > > > > > + if (!ofnode_valid(usb_phy_node)) {
>> > > > > > + log_err("%s: failed to find usb phy node\n", __func__);
>> > > > > > + return -EINVAL;
>> > > > > > + }
>> > > > >
>> > > > > dev_read_phandle() should replace the above
>> > > > >
>> > > >
>> > > > Goal of this piece is to get phy of_node by the phandle provided in the
>> > > > controller node. Controller node has not only single nvidia,phy phandle
>> > > > reference but also clock and reset reference. How will dev_read_phandle
>> > > > return me a phandle of "nvidia,phy"?
>> > > >
>> > > > https://github.com/clamor-s/u-boot/blob/master/arch/arm/dts/tegra30.dtsi#L798-L834
>> > > >
>> > > > > > + priv->xcvr_setup_use_fuses = ofnode_read_bool(
>> > > > > > + usb_phy_node, "nvidia,xcvr-setup-use-fuses");
>> > > > >
>> > > > > dev_read_bool()
>> > > > >
>> > > >
>> > > > This value is set in phy node, not controllers unfortunately.
>> > >
>> > > The question that comes to mind is, would it make sense to implement a PHY driver similar to what e.g. imx does -- drivers/phy/phy-imx8mq-usb.c -- for the tegra PHY ?
>> >
>> > Yes, but not by me or at least not now. I have already invested too much of my time and effort in this and I will not invest even more into refactoring all this code into 2 separate drivers. Existing code satisfies me apart from this small tweak.
>>
>> The PHY driver implementation is trivial, example is the imx driver above,
>> then just call phy on/off in the right place. Linux also has a PHY driver
>> for tegra, maybe you can reuse it ?
>
>The Linux USB PHY driver is something that in retrospect I would've done
>differently. The problem is that it shares resources (registers and
>clock/reset lines) with the USB controller and it's caused a lot of
>headaches to support it in Linux.
>
>Maybe within U-Boot this isn't such a big deal, but for Linux I would've
>preferred a single driver that is both a USB controller and a USB PHY. I
>suppose it could expose some sort of PHY object for abstraction, but
>that would probably be a bit of overkill since this is really only used
>within the USB controller driver.
PHY node can be parsed by controller for values used in setup without creating separate driver. I would even agree to implement this.
>Thierry
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