Re: [PATCH 1/4] drm/i915/dsi: abstract dsi bpp derivation from pixel format

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 12 May 2015, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Tue, May 12, 2015 at 05:20:38PM +0300, Jani Nikula wrote:
>> Nuke three copies of the same switch case.
>> 
>> Hopefully we can switch to a drm generic function later on, but that
>> will require us to swich to enum mipi_dsi_pixel_format first.
>> 
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_dsi_pll.c | 67 +++++++++++++-----------------------
>>  1 file changed, 24 insertions(+), 43 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
>> index cfd527765156..9ada06ec88e5 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi_pll.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
>> @@ -38,6 +38,27 @@
>>  #define DSI_HFP_PACKET_EXTRA_SIZE	6
>>  #define DSI_EOTP_PACKET_SIZE		4
>>  
>> +static int dsi_pixel_format_bpp(int pixel_format)
>> +{
>> +	int bpp;
>> +
>> +	switch (pixel_format) {
>> +	default:
>> +	case VID_MODE_FORMAT_RGB888:
>> +	case VID_MODE_FORMAT_RGB666_LOOSE:
>> +		bpp = 24;
>> +		break;
>> +	case VID_MODE_FORMAT_RGB666:
>> +		bpp = 18;
>> +		break;
>> +	case VID_MODE_FORMAT_RGB565:
>> +		bpp = 16;
>> +		break;
>> +	}
>> +
>> +	return bpp;
>> +}
>
> Optional bikeshed: Could return directly from the switch cases and avoid
> the local variable.

The compiler appears to automatically inline the function (*and* two
functions it is called from), so does not make a difference.

Thanks for the review.

BR,
Jani.

>
> But anyway:
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
>> +
>>  struct dsi_mnp {
>>  	u32 dsi_pll_ctrl;
>>  	u32 dsi_pll_div;
>> @@ -65,19 +86,7 @@ static u32 dsi_rr_formula(const struct drm_display_mode *mode,
>>  	u32 dsi_bit_clock_hz;
>>  	u32 dsi_clk;
>>  
>> -	switch (pixel_format) {
>> -	default:
>> -	case VID_MODE_FORMAT_RGB888:
>> -	case VID_MODE_FORMAT_RGB666_LOOSE:
>> -		bpp = 24;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB666:
>> -		bpp = 18;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB565:
>> -		bpp = 16;
>> -		break;
>> -	}
>> +	bpp = dsi_pixel_format_bpp(pixel_format);
>>  
>>  	hactive = mode->hdisplay;
>>  	vactive = mode->vdisplay;
>> @@ -137,21 +146,7 @@ static u32 dsi_rr_formula(const struct drm_display_mode *mode,
>>  static u32 dsi_clk_from_pclk(u32 pclk, int pixel_format, int lane_count)
>>  {
>>  	u32 dsi_clk_khz;
>> -	u32 bpp;
>> -
>> -	switch (pixel_format) {
>> -	default:
>> -	case VID_MODE_FORMAT_RGB888:
>> -	case VID_MODE_FORMAT_RGB666_LOOSE:
>> -		bpp = 24;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB666:
>> -		bpp = 18;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB565:
>> -		bpp = 16;
>> -		break;
>> -	}
>> +	u32 bpp = dsi_pixel_format_bpp(pixel_format);
>>  
>>  	/* DSI data rate = pixel clock * bits per pixel / lane count
>>  	   pixel clock is converted from KHz to Hz */
>> @@ -285,21 +280,7 @@ void vlv_disable_dsi_pll(struct intel_encoder *encoder)
>>  
>>  static void assert_bpp_mismatch(int pixel_format, int pipe_bpp)
>>  {
>> -	int bpp;
>> -
>> -	switch (pixel_format) {
>> -	default:
>> -	case VID_MODE_FORMAT_RGB888:
>> -	case VID_MODE_FORMAT_RGB666_LOOSE:
>> -		bpp = 24;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB666:
>> -		bpp = 18;
>> -		break;
>> -	case VID_MODE_FORMAT_RGB565:
>> -		bpp = 16;
>> -		break;
>> -	}
>> +	int bpp = dsi_pixel_format_bpp(pixel_format);
>>  
>>  	WARN(bpp != pipe_bpp,
>>  	     "bpp match assertion failure (expected %d, current %d)\n",
>> -- 
>> 2.1.4
>
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Jani Nikula, Intel Open Source Technology Center
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