[PATCH v3] staging: fbtft: fb_upd161704: Replace udelay() with usleep_range()

[PATCH v3] staging: fbtft: fb_upd161704: Replace udelay() with usleep_range()

[Abubakar Musa Samaila]

Replace udelay() calls inside the init_display() initialization
sequence with usleep_range() to avoid CPU busy-waiting. Since
init_display() runs in a non-atomic context, sleeping allows the CPU
to yield, improving power efficiency and system responsiveness.

Signed-off-by: Abubakar Musa Samaila <abubakarmusasamaila@gmail.com>
---
v3:
- Remove raw git headers from the email body per maintainer feedback.
- Add a descriptive commit message body explaining the rationale for
usleep_range().

v2:
- Send patch inline in the email body rather than as an attachment.
- No functional changes to the code diff itself.

v1:
 drivers/staging/fbtft/fb_upd161704.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/fbtft/fb_upd161704.c
b/drivers/staging/fbtft/fb_upd161704.c
index 7288140e7..94ae5bbf0 100644
--- a/drivers/staging/fbtft/fb_upd161704.c
+++ b/drivers/staging/fbtft/fb_upd161704.c
@@ -32,27 +32,27 @@ static int init_display(struct fbtft_par *par)

        /* oscillator start */
        write_reg(par, 0x003A, 0x0001); /*Oscillator 0: stop, 1: operation */
-       udelay(100);
+       usleep_range(100, 150);

        /* y-setting */
        write_reg(par, 0x0024, 0x007B); /* amplitude setting */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0025, 0x003B); /* amplitude setting */
        write_reg(par, 0x0026, 0x0034); /* amplitude setting */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0027, 0x0004); /* amplitude setting */
        write_reg(par, 0x0052, 0x0025); /* circuit setting 1 */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0053, 0x0033); /* circuit setting 2 */
        write_reg(par, 0x0061, 0x001C); /* adjustment V10 positive polarity */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0062, 0x002C); /* adjustment V9 negative polarity */
        write_reg(par, 0x0063, 0x0022); /* adjustment V34 positive polarity */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0064, 0x0027); /* adjustment V31 negative polarity */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0065, 0x0014); /* adjustment V61 negative polarity */
-       udelay(10);
+       usleep_range(10, 20);
        write_reg(par, 0x0066, 0x0010); /* adjustment V61 negative polarity */

        /* Basical clock for 1 line (BASECOUNT[7:0]) number specified */
@@ -60,7 +60,7 @@ static int init_display(struct fbtft_par *par)

        /* Power supply setting */
        write_reg(par, 0x0019, 0x0000); /* DC/DC output setting */
-       udelay(200);
+       usleep_range(200, 250);
        write_reg(par, 0x001A, 0x1000); /* DC/DC frequency setting */
        write_reg(par, 0x001B, 0x0023); /* DC/DC rising setting */
        write_reg(par, 0x001C, 0x0C01); /* Regulator voltage setting */
-- 
2.34.1

Re: [PATCH v3] staging: fbtft: fb_upd161704: Replace udelay() with usleep_range()

[Julia Lawall]

On Sun, 25 Oct 2026, Abubakar Musa Samaila wrote:

> Replace udelay() calls inside the init_display() initialization
> sequence with usleep_range() to avoid CPU busy-waiting. Since
> init_display() runs in a non-atomic context, sleeping allows the CPU
> to yield, improving power efficiency and system responsiveness.


The patch fails when I try to apply it to the staging-next tree.

julia

>
> Signed-off-by: Abubakar Musa Samaila <abubakarmusasamaila@gmail.com>
> ---
> v3:
> - Remove raw git headers from the email body per maintainer feedback.
> - Add a descriptive commit message body explaining the rationale for
> usleep_range().
>
> v2:
> - Send patch inline in the email body rather than as an attachment.
> - No functional changes to the code diff itself.
>
> v1:
>  drivers/staging/fbtft/fb_upd161704.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/staging/fbtft/fb_upd161704.c
> b/drivers/staging/fbtft/fb_upd161704.c
> index 7288140e7..94ae5bbf0 100644
> --- a/drivers/staging/fbtft/fb_upd161704.c
> +++ b/drivers/staging/fbtft/fb_upd161704.c
> @@ -32,27 +32,27 @@ static int init_display(struct fbtft_par *par)
>
>         /* oscillator start */
>         write_reg(par, 0x003A, 0x0001); /*Oscillator 0: stop, 1: operation */
> -       udelay(100);
> +       usleep_range(100, 150);
>
>         /* y-setting */
>         write_reg(par, 0x0024, 0x007B); /* amplitude setting */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0025, 0x003B); /* amplitude setting */
>         write_reg(par, 0x0026, 0x0034); /* amplitude setting */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0027, 0x0004); /* amplitude setting */
>         write_reg(par, 0x0052, 0x0025); /* circuit setting 1 */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0053, 0x0033); /* circuit setting 2 */
>         write_reg(par, 0x0061, 0x001C); /* adjustment V10 positive polarity */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0062, 0x002C); /* adjustment V9 negative polarity */
>         write_reg(par, 0x0063, 0x0022); /* adjustment V34 positive polarity */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0064, 0x0027); /* adjustment V31 negative polarity */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0065, 0x0014); /* adjustment V61 negative polarity */
> -       udelay(10);
> +       usleep_range(10, 20);
>         write_reg(par, 0x0066, 0x0010); /* adjustment V61 negative polarity */
>
>         /* Basical clock for 1 line (BASECOUNT[7:0]) number specified */
> @@ -60,7 +60,7 @@ static int init_display(struct fbtft_par *par)
>
>         /* Power supply setting */
>         write_reg(par, 0x0019, 0x0000); /* DC/DC output setting */
> -       udelay(200);
> +       usleep_range(200, 250);
>         write_reg(par, 0x001A, 0x1000); /* DC/DC frequency setting */
>         write_reg(par, 0x001B, 0x0023); /* DC/DC rising setting */
>         write_reg(par, 0x001C, 0x0C01); /* Regulator voltage setting */
> --
> 2.34.1
>

Re: [PATCH v3] staging: fbtft: fb_upd161704: Replace udelay() with usleep_range()

[Andy Shevchenko]

On Sun, Oct 25, 2026 at 03:22:30PM +0100, Abubakar Musa Samaila wrote:
> Replace udelay() calls inside the init_display() initialization
> sequence with usleep_range() to avoid CPU busy-waiting. Since
> init_display() runs in a non-atomic context, sleeping allows the CPU
> to yield, improving power efficiency and system responsiveness.

Please, slow down. I have already answered on very beginning version.
Don't waste time on this.

-- 
With Best Regards,
Andy Shevchenko