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

From: Konrad Dybcio
Date: Thu Feb 15 2024 - 12:48:43 EST


On 15.02.2024 15:17, Serge Semin wrote:
> On Thu, Feb 15, 2024 at 11:39:31AM +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@xxxxxxxxxx>
>> ---
>> Tested on Qualcomm SC8280XP CRD
>> ---
>> 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..abce6afceb91 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_MSLEEP_MAX);
>> }
>>
>> 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..3f145d6a8a31 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_MSLEEP_MAX 100
>
> Why do you use the _MAX suffix here? AFAICS any the timers normally
> ensures the lower boundary value of the wait-duration, not the upper
> one. So the more correct suffix would be _MIN. On the other hand, as
> Alexander correctly noted, using fsleep() would be more suitable at
> least from the maintainability point of view. Thus having a macro name
> like LINK_WAIT_USLEEP_MIN or just LINK_WAIT_SLEEP_US would be more
> appropriate. The later version is more preferable IMO.

Agree with SLEEP_US

Konrad