Re: [PATCH] staging: fbtft: fb_watterott: fix usleep_range is preferred over udelay

Hassan Shahbazi
2020-11-01T10:32:58Z

On Sun, Nov 01, 2020 at 07:39:48AM +0100, Greg KH wrote:
> On Sun, Nov 01, 2020 at 02:20:10AM +0200, Hassan Shahbazi wrote:
> > Fix the checkpath.pl issue on fb_watterott.c. write_vmem and
> > write_vmem_8bit functions are within non-atomic context and can
> > safely use usleep_range.
> > see Documentation/timers/timers-howto.txt
> >
> > Signed-off-by: Hassan Shahbazi <hassan@ninchat.com>
> > ---
> > drivers/staging/fbtft/fb_watterott.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/fbtft/fb_watterott.c b/drivers/staging/fbtft/fb_watterott.c
> > index 76b25df376b8..afcc86a17995 100644
> > --- a/drivers/staging/fbtft/fb_watterott.c
> > +++ b/drivers/staging/fbtft/fb_watterott.c
> > @@ -84,7 +84,7 @@ static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
> > par->txbuf.buf, 10 + par->info->fix.line_length);
> > if (ret < 0)
> > return ret;
> > - udelay(300);
> > + usleep_range(300, 310);
> > }
> >
> > return 0;
> > @@ -124,7 +124,7 @@ static int write_vmem_8bit(struct fbtft_par *par, size_t offset, size_t len)
> > par->txbuf.buf, 10 + par->info->var.xres);
> > if (ret < 0)
> > return ret;
> > - udelay(700);
> > + usleep_range(700, 710);
>
> How do you know that these ranges are ok? Are you able to test these
> changes with real hardware?
>
> thanks,
>
> greg k-h

No, I don't have the hardware to test with. I just used the current
value as the minimum and added an epsilon to it for the maximum
param.

best, hassan shahbazi