drm: atmel-hlcdc: use double rate for pixel clock only if supported

Doubled system clock should be used as pixel cock source only if this
is supported. This is emphasized by the value of
atmel_hlcdc_crtc::dc::desc::fixed_clksrc.

Fixes: a6eca2a ("drm: atmel-hlcdc: add config option for clock selection")
Signed-off-by: Claudiu Beznea <[email protected]>
Signed-off-by: Sam Ravnborg <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: <[email protected]> # v5.3+
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: claudiubeznea

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c

@@ -95,14 +95,14 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 		     (adj->crtc_hdisplay - 1) |
 		     ((adj->crtc_vdisplay - 1) << 16));
 
+	prate = clk_get_rate(crtc->dc->hlcdc->sys_clk);
+	mode_rate = adj->crtc_clock * 1000;
 	if (!crtc->dc->desc->fixed_clksrc) {
+		prate *= 2;
 		cfg |= ATMEL_HLCDC_CLKSEL;
 		mask |= ATMEL_HLCDC_CLKSEL;
 	}
 
-	prate = 2 * clk_get_rate(crtc->dc->hlcdc->sys_clk);
-	mode_rate = adj->crtc_clock * 1000;
-
 	div = DIV_ROUND_UP(prate, mode_rate);
 	if (div < 2) {
 		div = 2;