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

commit 07acf4bafe81dd37eff3fbcfbbdbc48084bc202b upstream.

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: a6eca2abdd42 ("drm: atmel-hlcdc: add config option for clock selection")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: <stable@vger.kernel.org> # v5.3+
Link: https://patchwork.freedesktop.org/patch/msgid/1576672109-22707-2-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index f2e73e6d46b8515bea140d8a9c74461b51aea2ea..5040ed8d08717620d35d54ed751b80395388a3cb 100644 (file)
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/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;