* Re: [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range()
2026-03-11 14:24 [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range() Anas Iqbal
@ 2026-03-11 14:48 ` Dan Carpenter
2026-03-11 14:56 ` Greg KH
2026-03-11 16:01 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: Dan Carpenter @ 2026-03-11 14:48 UTC (permalink / raw)
To: Anas Iqbal
Cc: andy, gregkh, linux-staging, dri-devel, linux-fbdev, linux-kernel
On Wed, Mar 11, 2026 at 02:24:07PM +0000, Anas Iqbal wrote:
> Replace udelay() with usleep_range() for a 250 microsecond delay
> as recommended by checkpatch.pl. usleep_range() avoids busy
> waiting and allows the scheduler to schedule other tasks.
>
> Signed-off-by: Anas Iqbal <mohd.abd.6602@gmail.com>
> ---
> drivers/staging/fbtft/fb_tinylcd.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/fbtft/fb_tinylcd.c b/drivers/staging/fbtft/fb_tinylcd.c
> index 9469248f2c50..51e6493b050f 100644
> --- a/drivers/staging/fbtft/fb_tinylcd.c
> +++ b/drivers/staging/fbtft/fb_tinylcd.c
> @@ -38,10 +38,10 @@ static int init_display(struct fbtft_par *par)
> write_reg(par, 0xE5, 0x00);
> write_reg(par, 0xF0, 0x36, 0xA5, 0x53);
> write_reg(par, 0xE0, 0x00, 0x35, 0x33, 0x00, 0x00, 0x00,
> - 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
> + 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
Don't do this.
1) It's unrelated.
2) The previous alignment was done deliberate to make it easier to read.
Checkpatch is not perfect so don't always do what it says.
> write_reg(par, MIPI_DCS_SET_PIXEL_FORMAT, 0x55);
> write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE);
> - udelay(250);
> + usleep_range(250, 500);
Do a search for init_display on lore
https://lore.kernel.org/all/?q=init_display
regards,
dan carpenter
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range()
2026-03-11 14:24 [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range() Anas Iqbal
2026-03-11 14:48 ` Dan Carpenter
@ 2026-03-11 14:56 ` Greg KH
2026-03-11 16:01 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: Greg KH @ 2026-03-11 14:56 UTC (permalink / raw)
To: Anas Iqbal; +Cc: andy, linux-staging, dri-devel, linux-fbdev, linux-kernel
On Wed, Mar 11, 2026 at 02:24:07PM +0000, Anas Iqbal wrote:
> Replace udelay() with usleep_range() for a 250 microsecond delay
> as recommended by checkpatch.pl. usleep_range() avoids busy
> waiting and allows the scheduler to schedule other tasks.
>
> Signed-off-by: Anas Iqbal <mohd.abd.6602@gmail.com>
> ---
> drivers/staging/fbtft/fb_tinylcd.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/fbtft/fb_tinylcd.c b/drivers/staging/fbtft/fb_tinylcd.c
> index 9469248f2c50..51e6493b050f 100644
> --- a/drivers/staging/fbtft/fb_tinylcd.c
> +++ b/drivers/staging/fbtft/fb_tinylcd.c
> @@ -38,10 +38,10 @@ static int init_display(struct fbtft_par *par)
> write_reg(par, 0xE5, 0x00);
> write_reg(par, 0xF0, 0x36, 0xA5, 0x53);
> write_reg(par, 0xE0, 0x00, 0x35, 0x33, 0x00, 0x00, 0x00,
> - 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
> + 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
Don't you think the original formatting makes more sense? And you did
not describe this change in the changelog :(
> write_reg(par, MIPI_DCS_SET_PIXEL_FORMAT, 0x55);
> write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE);
> - udelay(250);
> + usleep_range(250, 500);
This is a totally different change than above. And also one that keeps
getting rejected, please see the mailing list archives for details.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range()
2026-03-11 14:24 [PATCH] staging: fbtft: fb_tinylcd: replace udelay() with usleep_range() Anas Iqbal
2026-03-11 14:48 ` Dan Carpenter
2026-03-11 14:56 ` Greg KH
@ 2026-03-11 16:01 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: Andy Shevchenko @ 2026-03-11 16:01 UTC (permalink / raw)
To: Anas Iqbal
Cc: andy, gregkh, linux-staging, dri-devel, linux-fbdev, linux-kernel
On Wed, Mar 11, 2026 at 02:24:07PM +0000, Anas Iqbal wrote:
> Replace udelay() with usleep_range() for a 250 microsecond delay
> as recommended by checkpatch.pl. usleep_range() avoids busy
> waiting and allows the scheduler to schedule other tasks.
Now, read README here:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/staging/fbtft/README
and act accordingly.
If you have been mentored on this, show the above link to your mentors.
...
> write_reg(par, 0xE0, 0x00, 0x35, 0x33, 0x00, 0x00, 0x00,
> - 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
> + 0x00, 0x35, 0x33, 0x00, 0x00, 0x00);
Use the common sense here. This change won't be accepted.
...
> - udelay(250);
> + usleep_range(250, 500);
No.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 4+ messages in thread