Re: [PATCH v2] usb: cdnsp: fix L1 resume issue for RTL_REVISION_NEW_LPM version

Peter Chen (CIX)
2025-04-29T01:58:22Z

On 25-04-25 05:55:40, Pawel Laszczak wrote:
> The controllers with rtl version larger than
> RTL_REVISION_NEW_LPM (0x00002700) has bug which causes that controller
> doesn't resume from L1 state. It happens if after receiving LPM packet
> controller starts transitioning to L1 and in this moment the driver force
> resuming by write operation to PORTSC.PLS.
> It's corner case and happens when write operation to PORTSC occurs during
> device delay before transitioning to L1 after transmitting ACK
> time (TL1TokenRetry).
>
> Forcing transition from L1->L0 by driver for revision larger than
> RTL_REVISION_NEW_LPM is not needed, so driver can simply fix this issue
> through block call of cdnsp_force_l0_go function.
>
> Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
> cc: stable@vger.kernel.org
> Signed-off-by: Pawel Laszczak <pawell@cadence.com>

Acked-by: Peter Chen <peter.chen@kernel.org>

Peter

> ---
> Changelog:
> v2:
> - improved patch description
> - changed RTL_REVISION_NEW_LPM value
>
> drivers/usb/cdns3/cdnsp-gadget.c | 2 ++
> drivers/usb/cdns3/cdnsp-gadget.h | 3 +++
> drivers/usb/cdns3/cdnsp-ring.c | 3 ++-
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/cdns3/cdnsp-gadget.c b/drivers/usb/cdns3/cdnsp-gadget.c
> index 87f310841735..e64c8f7eb0c5 100644
> --- a/drivers/usb/cdns3/cdnsp-gadget.c
> +++ b/drivers/usb/cdns3/cdnsp-gadget.c
> @@ -1773,6 +1773,8 @@ static void cdnsp_get_rev_cap(struct cdnsp_device *pdev)
> reg += cdnsp_find_next_ext_cap(reg, 0, RTL_REV_CAP);
> pdev->rev_cap = reg;
>
> + pdev->rtl_revision = readl(&pdev->rev_cap->rtl_revision);
> +
> dev_info(pdev->dev, "Rev: %08x/%08x, eps: %08x, buff: %08x/%08x\n",
> readl(&pdev->rev_cap->ctrl_revision),
> readl(&pdev->rev_cap->rtl_revision),
> diff --git a/drivers/usb/cdns3/cdnsp-gadget.h b/drivers/usb/cdns3/cdnsp-gadget.h
> index 84887dfea763..357ddbe53917 100644
> --- a/drivers/usb/cdns3/cdnsp-gadget.h
> +++ b/drivers/usb/cdns3/cdnsp-gadget.h
> @@ -1357,6 +1357,7 @@ struct cdnsp_port {
> * @rev_cap: Controller Capabilities Registers.
> * @hcs_params1: Cached register copies of read-only HCSPARAMS1
> * @hcc_params: Cached register copies of read-only HCCPARAMS1
> + * @rtl_revision: Cached controller rtl revision.
> * @setup: Temporary buffer for setup packet.
> * @ep0_preq: Internal allocated request used during enumeration.
> * @ep0_stage: ep0 stage during enumeration process.
> @@ -1411,6 +1412,8 @@ struct cdnsp_device {
> __u32 hcs_params1;
> __u32 hcs_params3;
> __u32 hcc_params;
> + #define RTL_REVISION_NEW_LPM 0x2700
> + __u32 rtl_revision;
> /* Lock used in interrupt thread context. */
> spinlock_t lock;
> struct usb_ctrlrequest setup;
> diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
> index 46852529499d..fd06cb85c4ea 100644
> --- a/drivers/usb/cdns3/cdnsp-ring.c
> +++ b/drivers/usb/cdns3/cdnsp-ring.c
> @@ -308,7 +308,8 @@ static bool cdnsp_ring_ep_doorbell(struct cdnsp_device *pdev,
>
> writel(db_value, reg_addr);
>
> - cdnsp_force_l0_go(pdev);
> + if (pdev->rtl_revision < RTL_REVISION_NEW_LPM)
> + cdnsp_force_l0_go(pdev);
>
> /* Doorbell was set. */
> return true;
> --
> 2.43.0
>

--

Best regards,
Peter