2019-05-10 15:07:51

by Yannick FERTRE

Subject: [PATCH] drm/stm: ltdc: remove clk_round_rate comment

Clk_round_rate returns rounded clock without changing
the hardware in any way.
This function couldn't replace set_rate/get_rate calls.
Todo comment has been removed & a new log inserted.

Signed-off-by: Yannick Fertré <[email protected]>
---
drivers/gpu/drm/stm/ltdc.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 97912e2..2f8aa2e 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -507,20 +507,16 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
struct ltdc_device *ldev = crtc_to_ltdc(crtc);
int rate = mode->clock * 1000;

- /*
- * TODO clk_round_rate() does not work yet. When ready, it can
- * be used instead of clk_set_rate() then clk_get_rate().
- */
-
- clk_disable(ldev->pixel_clk);
if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
return false;
}
- clk_enable(ldev->pixel_clk);

adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;

+ DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
+ mode->clock, adjusted_mode->clock);
+
return true;
}

--
2.7.4

2019-05-10 16:41:54

by Philippe Cornu

Subject: Re: [PATCH] drm/stm: ltdc: remove clk_round_rate comment

Dear Yannick,
Thank you for your patch,

In your patch, you have removed clk_disable() & clk_enable().
Could you please double confirm ?

thanks
Philippe :-)


On 5/10/19 5:03 PM, Yannick Fertré wrote:
> Clk_round_rate returns rounded clock without changing
> the hardware in any way.
> This function couldn't replace set_rate/get_rate calls.
> Todo comment has been removed & a new log inserted.
>
> Signed-off-by: Yannick Fertré <[email protected]>
> ---
> drivers/gpu/drm/stm/ltdc.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 97912e2..2f8aa2e 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -507,20 +507,16 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
> struct ltdc_device *ldev = crtc_to_ltdc(crtc);
> int rate = mode->clock * 1000;
>
> - /*
> - * TODO clk_round_rate() does not work yet. When ready, it can
> - * be used instead of clk_set_rate() then clk_get_rate().
> - */
> -
> - clk_disable(ldev->pixel_clk);
> if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
> DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
> return false;
> }
> - clk_enable(ldev->pixel_clk);
>
> adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;
>
> + DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
> + mode->clock, adjusted_mode->clock);
> +
> return true;
> }
>
>

2019-05-13 15:42:21

by Yannick FERTRE

Subject: Re: [PATCH] drm/stm: ltdc: remove clk_round_rate comment

Dear Philippe,

you're right, clk_disable() & clk_enable() are necessary with STM32F4
SOC (not for STM32MP1).

I'll revert this part of the patch.

Many thanks


--
Yannick Fertré | TINA: 166 7152 | Tel: +33 244027152 | Mobile: +33 620600270
Microcontrollers and Digital ICs Group | Microcontrolleurs Division

On 5/10/19 6:40 PM, Philippe CORNU wrote:
> Dear Yannick,
> Thank you for your patch,
>
> In your patch, you have removed clk_disable() & clk_enable().
> Could you please double confirm ?
>
> thanks
> Philippe :-)
>
>
> On 5/10/19 5:03 PM, Yannick Fertré wrote:
>> Clk_round_rate returns rounded clock without changing
>> the hardware in any way.
>> This function couldn't replace set_rate/get_rate calls.
>> Todo comment has been removed & a new log inserted.
>>
>> Signed-off-by: Yannick Fertré <[email protected]>
>> ---
>> drivers/gpu/drm/stm/ltdc.c | 10 +++-------
>> 1 file changed, 3 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
>> index 97912e2..2f8aa2e 100644
>> --- a/drivers/gpu/drm/stm/ltdc.c
>> +++ b/drivers/gpu/drm/stm/ltdc.c
>> @@ -507,20 +507,16 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
>> struct ltdc_device *ldev = crtc_to_ltdc(crtc);
>> int rate = mode->clock * 1000;
>>
>> - /*
>> - * TODO clk_round_rate() does not work yet. When ready, it can
>> - * be used instead of clk_set_rate() then clk_get_rate().
>> - */
>> -
>> - clk_disable(ldev->pixel_clk);
>> if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
>> DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
>> return false;
>> }
>> - clk_enable(ldev->pixel_clk);
>>
>> adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;
>>
>> + DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
>> + mode->clock, adjusted_mode->clock);
>> +
>> return true;
>> }
>>
--
Yannick Fertré | TINA: 166 7152 | Tel: +33 244027152 | Mobile: +33 620600270
Microcontrollers and Digital ICs Group | Microcontrolleurs Division