linux-kernel - [PATCH v2] drm: mediatek: change the variable type of rdma threshold

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Date:   Fri, 19 May 2017 17:57:23 +0800
From:   Bibby Hsieh <bibby.hsieh@...iatek.com>
To:     David Airlie <airlied@...ux.ie>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>
CC:     Yingjoe Chen <yingjoe.chen@...iatek.com>,
        Cawa Cheng <cawa.cheng@...iatek.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        YT Shen <yt.shen@...iatek.com>,
        Thierry Reding <thierry.reding@...il.com>,
        CK Hu <ck.hu@...iatek.com>, Mao Huang <littlecvr@...omium.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>
Subject: [PATCH v2] drm: mediatek: change the variable type of rdma threshold

For some greater resolution, the rdma threshold
variable will overflow.

Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
index 0df05f9..9afdcd7 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
@@ -37,7 +37,7 @@
 #define DISP_REG_RDMA_FIFO_CON			0x0040
 #define RDMA_FIFO_UNDERFLOW_EN				BIT(31)
 #define RDMA_FIFO_PSEUDO_SIZE(bytes)			(((bytes) / 16) << 16)
-#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes)		((bytes) / 16)
+#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes) (((bytes) / 16) & 0x3ff)
 
 /**
  * struct mtk_disp_rdma - DISP_RDMA driver structure
@@ -109,7 +109,7 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
 			    unsigned int height, unsigned int vrefresh,
 			    unsigned int bpc)
 {
-	unsigned int threshold;
+	unsigned long long threshold;
 	unsigned int reg;
 
 	rdma_update_bits(comp, DISP_REG_RDMA_SIZE_CON_0, 0xfff, width);
@@ -121,7 +121,8 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
 	 * output threshold to 6 microseconds with 7/6 overhead to
 	 * account for blanking, and with a pixel depth of 4 bytes:
 	 */
-	threshold = width * height * vrefresh * 4 * 7 / 1000000;
+	threshold = (unsigned long long)width * height * vrefresh *
+		    4 * 7 / 1000000;
 	reg = RDMA_FIFO_UNDERFLOW_EN |
 	      RDMA_FIFO_PSEUDO_SIZE(SZ_8K) |
 	      RDMA_OUTPUT_VALID_FIFO_THRESHOLD(threshold);
-- 
1.9.1