[PATCH v1 1/1] usb: host: tegra: implement dts based xcvr setup
Marek Vasut
marex at denx.de
Sun Aug 20 21:10:17 CEST 2023
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 ?
Let's not add ad-hoc hacks, those are difficult to maintain in the long run.
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