Re: [PATCH v2] PCI: dwc: Use the correct sleep function in wait_for_link

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Mar 27, 2024 at 07:24:49PM +0100, Konrad Dybcio wrote:
> According to [1], msleep should be used for large sleeps, such as the
> 100-ish ms one in this function. Comply with the guide and use it.
> 
> [1] https://www.kernel.org/doc/Documentation/timers/timers-howto.txt
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Thanks for fixing this up!

No need to repost, but whoever applies this, please update the subject
to be more specific:

s/the correct sleep function/msleep()/
s/wait_for_link/dw_pcie_wait_for_link()/

Also update the doc link to something like this since timers-howto.txt
no longer exists, and even timers-howto might be renamed or moved in
the future:

https://docs.kernel.org/6.8/timers/timers-howto.html

> ---
> Tested on Qualcomm SC8280XP CRD
> ---
> Changes in v2:
> - Rename the define
> - Sleep for 90ms (the lower boundary) instead of 100
> - Link to v1: https://lore.kernel.org/r/20240215-topic-pci_sleep-v1-1-7ac79ac9739a@linaro.org
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 2 +-
>  drivers/pci/controller/dwc/pcie-designware.h | 3 +--
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 250cf7f40b85..62915e4b2ebd 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -655,7 +655,7 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
>  		if (dw_pcie_link_up(pci))
>  			break;
>  
> -		usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
> +		msleep(LINK_WAIT_SLEEP_MS);
>  	}
>  
>  	if (retries >= LINK_WAIT_MAX_RETRIES) {
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 26dae4837462..b17e8ff54f55 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -63,8 +63,7 @@
>  
>  /* Parameters for the waiting for link up routine */
>  #define LINK_WAIT_MAX_RETRIES		10
> -#define LINK_WAIT_USLEEP_MIN		90000
> -#define LINK_WAIT_USLEEP_MAX		100000
> +#define LINK_WAIT_SLEEP_MS		90
>  
>  /* Parameters for the waiting for iATU enabled routine */
>  #define LINK_WAIT_MAX_IATU_RETRIES	5
> 
> ---
> base-commit: 26074e1be23143b2388cacb36166766c235feb7c
> change-id: 20240215-topic-pci_sleep-368108a1fb6f
> 
> Best regards,
> -- 
> Konrad Dybcio <konrad.dybcio@linaro.org>
>