linux-kernel - [PATCH v2] drm/bridge/sii8620: fix display modes validation

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Date:   Fri, 02 Feb 2018 11:54:25 +0100
From:   Maciej Purski <m.purski@...sung.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-kernel@...r.kernel.org, Maciej Purski <m.purski@...sung.com>
Subject: [PATCH v2] drm/bridge/sii8620: fix display modes validation

Current implementation of mode_valid() and mode_fixup() callbacks
handle packed pixel modes improperly.

Fix it by using proper maximum clock values from the documentation.

Signed-off-by: Maciej Purski <m.purski@...sung.com>

---
Changes in v2:
- simplify is_packing_required() function
- fix uninitialized variable detected by kbuild robot in mode_valid()
---
 drivers/gpu/drm/bridge/sil-sii8620.c | 81 +++++++++++++++++++-----------------
 1 file changed, 42 insertions(+), 39 deletions(-)

diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
index 5168783..912d8c2 100644
--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -34,8 +34,11 @@
 
 #define SII8620_BURST_BUF_LEN 288
 #define VAL_RX_HDMI_CTRL2_DEFVAL VAL_RX_HDMI_CTRL2_IDLE_CNT(3)
-#define MHL1_MAX_LCLK 225000
-#define MHL3_MAX_LCLK 600000
+
+#define MHL1_MAX_PCLK 75000
+#define MHL1_MAX_PCLK_PP_MODE 150000
+#define MHL3_MAX_PCLK 200000
+#define MHL3_MAX_PCLK_PP_MODE 300000
 
 enum sii8620_mode {
 	CM_DISCONNECTED,
@@ -2123,61 +2126,61 @@ static void sii8620_detach(struct drm_bridge *bridge)
 	rc_unregister_device(ctx->rc_dev);
 }
 
+static int sii8620_is_packing_required(struct sii8620 *ctx,
+				 const struct drm_display_mode *mode)
+{
+	int max_pclk, max_pclk_pp_mode;
+
+	if (sii8620_is_mhl3(ctx)) {
+		max_pclk = MHL3_MAX_PCLK;
+		max_pclk_pp_mode = MHL3_MAX_PCLK_PP_MODE;
+	} else {
+		max_pclk = MHL1_MAX_PCLK;
+		max_pclk_pp_mode = MHL1_MAX_PCLK_PP_MODE;
+	}
+
+	if (mode->clock < max_pclk)
+		return 0;
+	else if (mode->clock < max_pclk_pp_mode)
+		return 1;
+	else
+		return -1;
+}
+
 static enum drm_mode_status sii8620_mode_valid(struct drm_bridge *bridge,
 					 const struct drm_display_mode *mode)
 {
 	struct sii8620 *ctx = bridge_to_sii8620(bridge);
+	int pack_required = sii8620_is_packing_required(ctx, mode);
 	bool can_pack = ctx->devcap[MHL_DCAP_VID_LINK_MODE] &
 			MHL_DCAP_VID_LINK_PPIXEL;
-	unsigned int max_pclk = sii8620_is_mhl3(ctx) ? MHL3_MAX_LCLK :
-						       MHL1_MAX_LCLK;
-	max_pclk /= can_pack ? 2 : 3;
 
-	return (mode->clock > max_pclk) ? MODE_CLOCK_HIGH : MODE_OK;
+	switch (pack_required) {
+	case 0:
+		return MODE_OK;
+	case 1:
+		return (can_pack) ? MODE_OK : MODE_CLOCK_HIGH;
+	default:
+		return MODE_CLOCK_HIGH;
+	}
 }
 
+
 static bool sii8620_mode_fixup(struct drm_bridge *bridge,
 			       const struct drm_display_mode *mode,
 			       struct drm_display_mode *adjusted_mode)
 {
 	struct sii8620 *ctx = bridge_to_sii8620(bridge);
-	int max_lclk;
-	bool ret = true;
 
 	mutex_lock(&ctx->lock);
 
-	max_lclk = sii8620_is_mhl3(ctx) ? MHL3_MAX_LCLK : MHL1_MAX_LCLK;
-	if (max_lclk > 3 * adjusted_mode->clock) {
-		ctx->use_packed_pixel = 0;
-		goto end;
-	}
-	if ((ctx->devcap[MHL_DCAP_VID_LINK_MODE] & MHL_DCAP_VID_LINK_PPIXEL) &&
-	    max_lclk > 2 * adjusted_mode->clock) {
-		ctx->use_packed_pixel = 1;
-		goto end;
-	}
-	ret = false;
-end:
-	if (ret) {
-		u8 vic = drm_match_cea_mode(adjusted_mode);
-
-		if (!vic) {
-			union hdmi_infoframe frm;
-			u8 mhl_vic[] = { 0, 95, 94, 93, 98 };
-
-			/* FIXME: We need the connector here */
-			drm_hdmi_vendor_infoframe_from_display_mode(
-				&frm.vendor.hdmi, NULL, adjusted_mode);
-			vic = frm.vendor.hdmi.vic;
-			if (vic >= ARRAY_SIZE(mhl_vic))
-				vic = 0;
-			vic = mhl_vic[vic];
-		}
-		ctx->video_code = vic;
-		ctx->pixel_clock = adjusted_mode->clock;
-	}
+	ctx->use_packed_pixel = sii8620_is_packing_required(ctx, adjusted_mode);
+	ctx->video_code = drm_match_cea_mode(adjusted_mode);
+	ctx->pixel_clock = adjusted_mode->clock;
+
 	mutex_unlock(&ctx->lock);
-	return ret;
+
+	return true;
 }
 
 static const struct drm_bridge_funcs sii8620_bridge_funcs = {
-- 
2.7.4