drm/radeon/kms/atom: get better min pixel clock info

Where supported use ulMinPixelClockPLL_Output rather than
usMinPixelClockPLL_Output for pll_out_min.  This seems to
improve pll selection on some boards.
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -641,8 +641,12 @@ bool radeon_atom_get_clock_info(struct drm_device *dev)
 		    le16_to_cpu(firmware_info->info.usReferenceClock);
 		p1pll->reference_div = 0;
 
+		if (crev < 2)
 			p1pll->pll_out_min =
 				le16_to_cpu(firmware_info->info.usMinPixelClockPLL_Output);
+		else
+			p1pll->pll_out_min =
+				le32_to_cpu(firmware_info->info_12.ulMinPixelClockPLL_Output);
 		p1pll->pll_out_max =
 		    le32_to_cpu(firmware_info->info.ulMaxPixelClockPLL_Output);