[PATCH libdrm v3] modetest: Add support for setting mode having floating vertical refresh rate

[Ville Syrjälä]

On Mon, Nov 11, 2019 at 03:47:22AM -0800, Devarsh Thakkar wrote:
> For the scenario where user may require to modeset with a mode
> supporting a fractional value for vertical refresh-rate,
> appropriate mode can be selected by searching for mode
> having matching fractional vertical refresh rate using
> below equation.
> 
> vrefresh = (1000 * pixel clock) / (htotal * vtotal) Hz.
> 
> We do this way since driver doesn't return float value of vrefresh
> as it use int for vrefresh in struct drm_mode_info, but we can derive
> the actual value using pixel clock, horizontal total size and
> vertical total size values.
> 
> So for e.g. if user want to select mode having 59.94 Hz as refresh rate
> then with this patch it be can done as shown in below command,
> given there is an appropriate mode is available :
> 
> modetest -M xlnx -s 39:1920x1080-59.94 at BG24 -v
> 
> NOTE: Above command was tested on xilinx DRM driver with DP
> monitor which was supporting mode having 59.94 Hz refresh rate.
> 
> Signed-off-by: Devarsh Thakkar <devarsh.thakkar at xilinx.com>
> ---
> V2: Update commit message
> V3: Update with below changes as per review comments :
>   1) Use epsilon for vrefresh comparison
>   2) Use implicit type-casting wherever possible

Please keep these in the commit msg proper. We prefer these things
to hang around even when the patch gets pushed.

Patch lgtm.
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> 
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You should do something to eliminate this. Doesn't make sense for
open source stuff.

-- 
Ville Syrjälä
Intel