linux-kernel - Re: [PATCH] usb: cdnsp: fix L1 resume issue for RTL_REVISION_NEW

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Message-ID: <20250424060748.GA3601935@nchen-desktop>
Date: Thu, 24 Apr 2025 14:07:48 +0800
From: "Peter Chen (CIX)" <peter.chen@...nel.org>
To: Pawel Laszczak <pawell@...ence.com>
Cc: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: cdnsp: fix L1 resume issue for RTL_REVISION_NEW_LPM
 version

On 25-04-23 11:43:03, Pawel Laszczak wrote:
> The controllers with rtl version greeter than
less 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 greeter than

%s/greeter/larger

> 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@...r.kernel.org
> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> ---
>  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 7f5534db2086..4824a10df07e 100644
> --- a/drivers/usb/cdns3/cdnsp-gadget.c
> +++ b/drivers/usb/cdns3/cdnsp-gadget.c
> @@ -1793,6 +1793,8 @@ 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 87ac0cd113e7..fa02f861217f 100644
> --- a/drivers/usb/cdns3/cdnsp-gadget.h
> +++ b/drivers/usb/cdns3/cdnsp-gadget.h
> @@ -1360,6 +1360,7 @@ 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.
> @@ -1414,6 +1415,8 @@ struct cdnsp_device {
>  	__u32 hcs_params1;
>  	__u32 hcs_params3;
>  	__u32 hcc_params;
> +	#define RTL_REVISION_NEW_LPM 0x00002701

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);

Pawel, it may not solve all issues for controllers which RTL version
is less than 0x2700, do you have any other patches for it?

-- 

Best regards,
Peter