Re: [PATCH] usb: dwc3: exynos: remove usb_phy_generic support

From: Vivek Gautam
Date: Wed Aug 27 2014 - 14:12:32 EST

Hi Baltlomiej,


On Wed, Aug 27, 2014 at 1:22 PM, Bartlomiej Zolnierkiewicz
<b.zolnierkie@xxxxxxxxxxx> wrote:
> dwc3 driver is using the new Exynos5 SoC series USB DRD PHY driver
> (PHY_EXYNOS5_USBDRD which selects GENERIC_PHY) as can be seen by
> looking at the following commits:
>
> 7a4cf0fde054 ("ARM: dts: Update DWC3 usb controller to use new
> phy driver for exynos5250")
>
> f070267b5fc1 ("ARM: dts: Enable support for DWC3 controller for
> exynos5420")
>
> Thus remove unused usb_phy_generic support from dwc3 Exynos glue
> layer.
>
> [ The code that is being removed is harmful in the context of
> multi_v7_defconfig and enabling "EHCI support for Samsung
> S5P/EXYNOS SoC Series" (USB_EHCI_EXYNOS) + "OHCI support for
> Samsung S5P/EXYNOS SoC Series" (USB_OHCI_EXYNOS) because "EHCI
> support for OMAP3 and later chips" (USB_EHCI_HCD_OMAP) selects
> "NOP USB Transceiver Driver" (NOP_USB_XCEIV). NOP USB driver
> attaches itself to usb_phy_generic platform devices created by
> dwc3 Exynos glue layer and later causes Exynos EHCI driver to
> fail probe and Exynos OHCI driver to hang on probe (as observed
> on Exynos5250 Arndale board). ]

The issue with EHCI and OHCI on exynos platforms is that until now
they also request
usb-phy and only later if they don't find one, they go ahead and get a
'phy' generic.

Fortunately we missed this issue with exynos_defconfig, and as you rightly
mentioned with multi_v7_defconfig, the NOP_USB_XCEIV gets enabled and
EHCI and OHCI exynos get no-op usb-phy, which actually blocks EHCI/OHCI from
initializing the real PHYs.

This issue is resolved with patches:
[PATCH v2 1/2] usb: host: ehci-exynos: Remove unnecessary usb-phy support
[PATCH v2 2/2] usb: host: ohci-exynos: Remove unnecessary usb-phy support
wherein we are completely removing the usb-phy support from ehci/ohci-exynos.
So with these patches we should not see the issue mentioned by you.

Now for the DWC3 part, the usb-phy part was added to use register two
separate no-op-xceivers of USB2_PHY type and USB3_PHY type,
so that platforms with no separate PHY can still be able to use dwc3.

>
> Cc: Olof Johansson <olof@xxxxxxxxx>
> Cc: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
> Cc: Vivek Gautam <gautam.vivek@xxxxxxxxxxx>
> Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> ---
> drivers/usb/dwc3/dwc3-exynos.c | 68 -----------------------------------------
> 1 file changed, 1 insertion(+), 67 deletions(-)
>
> Index: b/drivers/usb/dwc3/dwc3-exynos.c
> ===================================================================
> --- a/drivers/usb/dwc3/dwc3-exynos.c 2014-08-25 14:57:04.991781925 +0200
> +++ b/drivers/usb/dwc3/dwc3-exynos.c 2014-08-27 09:16:38.312617727 +0200
> @@ -23,15 +23,12 @@
> #include <linux/platform_data/dwc3-exynos.h>
> #include <linux/dma-mapping.h>
> #include <linux/clk.h>
> -#include <linux/usb/otg.h>
> -#include <linux/usb/usb_phy_generic.h>
> +#include <linux/pm_runtime.h>
> #include <linux/of.h>
> #include <linux/of_platform.h>
> #include <linux/regulator/consumer.h>
>
> struct dwc3_exynos {
> - struct platform_device *usb2_phy;
> - struct platform_device *usb3_phy;
> struct device *dev;
>
> struct clk *clk;
> @@ -39,61 +36,6 @@ struct dwc3_exynos {
> struct regulator *vdd10;
> };
>
> -static int dwc3_exynos_register_phys(struct dwc3_exynos *exynos)
> -{
> - struct usb_phy_generic_platform_data pdata;
> - struct platform_device *pdev;
> - int ret;
> -
> - memset(&pdata, 0x00, sizeof(pdata));
> -
> - pdev = platform_device_alloc("usb_phy_generic", PLATFORM_DEVID_AUTO);
> - if (!pdev)
> - return -ENOMEM;
> -
> - exynos->usb2_phy = pdev;
> - pdata.type = USB_PHY_TYPE_USB2;
> - pdata.gpio_reset = -1;
> -
> - ret = platform_device_add_data(exynos->usb2_phy, &pdata, sizeof(pdata));
> - if (ret)
> - goto err1;
> -
> - pdev = platform_device_alloc("usb_phy_generic", PLATFORM_DEVID_AUTO);
> - if (!pdev) {
> - ret = -ENOMEM;
> - goto err1;
> - }
> -
> - exynos->usb3_phy = pdev;
> - pdata.type = USB_PHY_TYPE_USB3;
> -
> - ret = platform_device_add_data(exynos->usb3_phy, &pdata, sizeof(pdata));
> - if (ret)
> - goto err2;
> -
> - ret = platform_device_add(exynos->usb2_phy);
> - if (ret)
> - goto err2;
> -
> - ret = platform_device_add(exynos->usb3_phy);
> - if (ret)
> - goto err3;
> -
> - return 0;
> -
> -err3:
> - platform_device_del(exynos->usb2_phy);
> -
> -err2:
> - platform_device_put(exynos->usb3_phy);
> -
> -err1:
> - platform_device_put(exynos->usb2_phy);
> -
> - return ret;
> -}
> -
> static int dwc3_exynos_remove_child(struct device *dev, void *unused)
> {
> struct platform_device *pdev = to_platform_device(dev);
> @@ -127,12 +69,6 @@ static int dwc3_exynos_probe(struct plat
>
> platform_set_drvdata(pdev, exynos);
>
> - ret = dwc3_exynos_register_phys(exynos);
> - if (ret) {
> - dev_err(dev, "couldn't register PHYs\n");
> - return ret;
> - }
> -
> clk = devm_clk_get(dev, "usbdrd30");
> if (IS_ERR(clk)) {
> dev_err(dev, "couldn't get clock\n");
> @@ -194,8 +130,6 @@ static int dwc3_exynos_remove(struct pla
> struct dwc3_exynos *exynos = platform_get_drvdata(pdev);
>
> device_for_each_child(&pdev->dev, NULL, dwc3_exynos_remove_child);
> - platform_device_unregister(exynos->usb2_phy);
> - platform_device_unregister(exynos->usb3_phy);
>
> clk_disable_unprepare(exynos->clk);
>
>
> --
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--
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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