Thread (39 messages) 39 messages, 4 authors, 2017-02-24
STALE3380d

[PATCH 05/12] drm/ast: Fix calculation of MCLK

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2017-02-23 22:54:45
Also in: dri-devel
Subsystem: drm driver for ast server graphics chips, drm drivers, drm drivers and misc gpu patches, the rest · Maintainers: Dave Airlie, David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Linus Torvalds

Some braces were missing causing an incorrect calculation.

Y.C. Chen from Aspeed provided me with the right formula
which I tested on AST2400 and 2500.

The MCLK isn't currently used by the driver (it will eventually
to filter modes) so the issue isn't catastrophic.

Also make the printed value a bit more meaningful

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 drivers/gpu/drm/ast/ast_main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 718c15b..d194af3 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -352,7 +352,7 @@ static int ast_get_dram_info(struct drm_device *dev)
 		div = 0x1;
 		break;
 	}
-	ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div * 1000);
+	ast->mclk = ref_pll * (num + 2) / ((denum + 2) * (div * 1000));
 	return 0;
 }
 
@@ -496,7 +496,9 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
 		if (ret)
 			goto out_free;
 		ast->vram_size = ast_get_vram_info(dev);
-		DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size);
+		DRM_INFO("dram MCLK=%u Mhz type=%d bus_width=%d size=%08x\n",
+			 ast->mclk, ast->dram_type,
+			 ast->dram_bus_width, ast->vram_size);
 	}
 
 	if (need_post)
-- 
2.9.3
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