On 1/12/2017 7:15 AM, Nicholas Mc Guire wrote:
> ulseep_range() uses hrtimers and provides no advantage over msleep()
> for larger delays. Fix up the 100ms delays here passing the adjusted "min"
> value to msleep(). This helps reduce the load on the hrtimer subsystem.
>
> Link:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.org_lkml_2017_1_11_377&d=DgIBAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=U3o8uKoKhWme5_V9D-eeCkB11BFwt4KvWztBgdE9ZpA&m=dvQDbbH_QF2kZjARIDPimFAK95z8eOnw04feJuHCrJg&s=Prc0m1oUG4u8n8TFK-fdgzitMzE2ep6pM3L6y_DQeRs&e=
>
> Fixes: commit 2938fc63e0c2 ("usb: dwc2: Properly account for the force mode
> delays")
> Signed-off-by: Nicholas Mc Guire
> ---
> Problem was found by cocinelle script.
>
> Note that this originally was an msleep(25) then commit 2938fc63e0c2
> ("usb: dwc2: Properly account for the force mode delays") changed this
> to usleep_range(10,11) with the comment in the function head:
>
> After clearing the bits, wait up to 100 ms to account for any
> potential IDDIG filter delay...
>
> but without explaining why the API was switched to usleep_range() here
> It does not look like there is any reason for using a high resolution
> timer here - the stated requirement is clearly satisfied by msleep(100)
> as well. But it originally was usleep_range(15, 16) in
> commit 09c96980dc72 ("usb: dwc2: Add functions to set and clear force mode")
> so not sure if I am not overlooking some reason for the highrestimer here ?
>
> This needs to be clarified by someone that knows the details and history
> of this device/driver.
>
> Patch was compile tested with: x86_64_defconfig + CONFIG_USB_DWC2
>
> Patch is aginast 4.10-rc3 (localversion-next is next-20170112)
>
> drivers/usb/dwc2/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
> index 11d8ae9..439a21b 100644
> --- a/drivers/usb/dwc2/core.c
> +++ b/drivers/usb/dwc2/core.c
> @@ -455,7 +455,7 @@ void dwc2_clear_force_mode(struct dwc2_hsotg *hsotg)
> dwc2_writel(gusbcfg, hsotg->regs + GUSBCFG);
>
> if (dwc2_iddig_filter_enabled(hsotg))
> - usleep_range(10, 11);
> + msleep(100);
> }
>
> /*
>
+Felipe
Acked-by: John Youn
John
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