drm/rcar-du: dsi: Handle both DRM_MODE_FLAG_N.SYNC and !DRM_MODE_FLAG_P.SYNC

Since commit 94fe479fae96 ("drm/rcar-du: dsi: Clean up handling of DRM mode flags")
the driver does not set TXVMVPRMSET0R_VSPOL_LOW and TXVMVPRMSET0R_HSPOL_LOW
for modes which set neither DRM_MODE_FLAG_[PN].SYNC. The previous behavior
was to assume that neither flag means DRM_MODE_FLAG_N.SYNC . Restore the
previous behavior for maximum compatibility.

The change of behavior is visible below, consider Vertical mode->flags
for simplicity sake, although the same applies to Horizontal ones:

Before 94fe479fae96 ("drm/rcar-du: dsi: Clean up handling of DRM mode flags") :

- DRM_MODE_FLAG_PVSYNC => vprmset0r |= 0
- DRM_MODE_FLAG_NVSYNC => vprmset0r |= TXVMVPRMSET0R_VSPOL_LOW
- Neither DRM_MODE_FLAG_[PN]VSYNC => vprmset0r |= TXVMVPRMSET0R_VSPOL_LOW

After 94fe479fae96 ("drm/rcar-du: dsi: Clean up handling of DRM mode flags") :

- DRM_MODE_FLAG_PVSYNC => vprmset0r |= 0
- DRM_MODE_FLAG_NVSYNC => vprmset0r |= TXVMVPRMSET0R_VSPOL_LOW
- Neither DRM_MODE_FLAG_[PN]VSYNC => vprmset0r |= 0 <---------- This broke

The "Neither" case behavior is different, because DRM_MODE_FLAG_N[HV]SYNC is
really not equivalent !DRM_MODE_FLAG_P[HV]SYNC .

Fixes: 94fe479fae96 ("drm/rcar-du: dsi: Clean up handling of DRM mode flags")
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://patch.msgid.link/20251202181146.138365-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
index 9413b76d0bfce0979aa047ccb908265c99c72b3d..4ef2e3c129ed7e2ae0477f8e2ed5cb876ba13347 100644 (file)
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c
@@ -492,9 +492,9 @@ static void rcar_mipi_dsi_set_display_timing(struct rcar_mipi_dsi *dsi,
 
        /* Configuration for Video Parameters, input is always RGB888 */
        vprmset0r = TXVMVPRMSET0R_BPP_24;
-       if (mode->flags & DRM_MODE_FLAG_NVSYNC)
+       if (!(mode->flags & DRM_MODE_FLAG_PVSYNC))
                vprmset0r |= TXVMVPRMSET0R_VSPOL_LOW;
-       if (mode->flags & DRM_MODE_FLAG_NHSYNC)
+       if (!(mode->flags & DRM_MODE_FLAG_PHSYNC))
                vprmset0r |= TXVMVPRMSET0R_HSPOL_LOW;
 
        vprmset1r = TXVMVPRMSET1R_VACTIVE(mode->vdisplay)