Re: [PATCH] usb: cdnsp: fix wakeup from S3 after controller context loss

[Peter Chen]

On 26-07-23 13:28:27, Pawel Laszczak via B4 Relay wrote:
> From: Pawel Laszczak <pawell@xxxxxxxxxxx>
> 

Hi Pawel,

I have already left nxp six years ago, please change my email
as peter.chen@xxxxxxxxxx.

> CDNSP controller loses its runtime register programming across S3
> suspend/resume.

It is not always true, it depends on SoC implementation. For some
SoCs (like CIX P1), the controller power still exists when the
system at S3.

> After resume the operational and interrupter registers
> may contain reset values, which prevents the gadget side from recovering
> correctly and breaks wakeup from S3.
> 
> Fix this by reprogramming the controller state required for normal
> operation after resume, including the command ring, DCBAA pointer,
> doorbell base, event ring, ERST base/size and event ring dequeue
> pointer.
> 
> Move the basic controller register programming out of the one-time memory
> initialization path and make it reusable from the resume path. Also
> separate ring allocation from ring initialization so that rings can be
> reinitialized without reallocating DMA memory.
> 
> This fixes S3 resume on systems where the controller register context is
> lost while keeping the existing DMA allocations intact.

With your fix, does device mode wakeup still work, does affect the SoC
like I mentioned CIX P1 which keeps power at S3?

> @@ -1575,9 +1576,13 @@ irqreturn_t cdnsp_thread_irq_handler(int irq, void *data)
>  irqreturn_t cdnsp_irq_handler(int irq, void *priv)
>  {
>  	struct cdnsp_device *pdev = (struct cdnsp_device *)priv;
> +	struct cdns *cdns = dev_get_drvdata(pdev->dev);
>  	u32 irq_pending;
>  	u32 status;
>  
> +	if (cdns->in_lpm)
> +		return IRQ_NONE;
> +

If the interrupt happens before cdns->in_lpm is clear, there will be no one
handles interrupt issue.

-- 

Thanks,
Peter Chen