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

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

[Yannick Fertré]

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 <yannick.fertre@st.com>
---
 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

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

[Philippe CORNU]

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 <yannick.fertre@st.com>
> ---
>   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;
>   }
>   
> 

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

[Yannick FERTRE]

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 <yannick.fertre@st.com>
>> ---
>>    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