linux-kernel - Re: [PATCH] Revert "usb: dwc3: disable USB core PHY management"

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Message-ID: <e870459c-70e8-b4f3-ef7e-4dde0e952b3d@samsung.com>
Date:   Thu, 3 Nov 2022 16:19:17 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Johan Hovold <johan+linaro@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>, stable@...r.kernel.org
Subject: Re: [PATCH] Revert "usb: dwc3: disable USB core PHY management"

On 03.11.2022 15:46, Johan Hovold wrote:
> This reverts commit 6000b8d900cd5f52fbcd0776d0cc396e88c8c2ea.
>
> The offending commit disabled the USB core PHY management as the dwc3
> already manages the PHYs in question.
>
> Unfortunately some platforms have started relying on having USB core
> also controlling the PHY and this is specifically currently needed on
> some Exynos platforms for PHY calibration or connected device may fail
> to enumerate.
>
> The PHY calibration was previously handled in the dwc3 driver, but to
> work around some issues related to how the dwc3 driver interacts with
> xhci (e.g. using multiple drivers) this was moved to USB core by commits
> 34c7ed72f4f0 ("usb: core: phy: add support for PHY calibration") and
> a0a465569b45 ("usb: dwc3: remove generic PHY calibrate() calls").
>
> The same PHY obviously should not be controlled from two different
> places, which for example do no agree on the PHY mode or power state
> during suspend, but as the offending patch was backported to stable,
> let's revert it for now.
>
> Reported-by: Stefan Agner <stefan@...er.ch>
> Link: https://lore.kernel.org/lkml/808bdba846bb60456adf10a3016911ee@agner.ch/
> Fixes: 6000b8d900cd ("usb: dwc3: disable USB core PHY management")
> Cc: stable@...r.kernel.org
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>   drivers/usb/dwc3/host.c | 10 ----------
>   1 file changed, 10 deletions(-)
>
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index a7154fe8206d..f6f13e7f1ba1 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -11,13 +11,8 @@
>   #include <linux/of.h>
>   #include <linux/platform_device.h>
>   
> -#include "../host/xhci-plat.h"
>   #include "core.h"
>   
> -static const struct xhci_plat_priv dwc3_xhci_plat_priv = {
> -	.quirks = XHCI_SKIP_PHY_INIT,
> -};
> -
>   static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,
>   					int irq, char *name)
>   {
> @@ -97,11 +92,6 @@ int dwc3_host_init(struct dwc3 *dwc)
>   		goto err;
>   	}
>   
> -	ret = platform_device_add_data(xhci, &dwc3_xhci_plat_priv,
> -					sizeof(dwc3_xhci_plat_priv));
> -	if (ret)
> -		goto err;
> -
>   	memset(props, 0, sizeof(struct property_entry) * ARRAY_SIZE(props));
>   
>   	if (dwc->usb3_lpm_capable)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland