[PATCH 2/3] drm/ingenic: ipu: Remove YUV422 from supported formats on JZ4725B

[Paul Cercueil]

When configuring the IPU for packed YUV 4:2:2, depending on the scaling
ratios given by the source and destination resolutions, it is possible
to crash the IPU block beyond repair, to the point where a software
reset of the IP does not fix it. This can happen anytime, in the first
few frames, or after dozens of minutes. The same crash also happens when
the IPU is fully controlled by the LCD controller (in that case no HW
register is written at any moment after startup), which points towards a
hardware bug.

Thanksfully multiplanar YUV is not affected.

Until this bug is fixed or worked around, address this issue by removing
support for YUV 4:2:2 on the IPU of the JZ4725B.

Signed-off-by: Paul Cercueil <paul at crapouillou.net>
---
 drivers/gpu/drm/ingenic/ingenic-ipu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/ingenic/ingenic-ipu.c b/drivers/gpu/drm/ingenic/ingenic-ipu.c
index 7eae56fa92ea..f4f0abcd6692 100644
--- a/drivers/gpu/drm/ingenic/ingenic-ipu.c
+++ b/drivers/gpu/drm/ingenic/ingenic-ipu.c
@@ -795,10 +795,16 @@ static int ingenic_ipu_remove(struct platform_device *pdev)
 }
 
 static const u32 jz4725b_ipu_formats[] = {
+	/*
+	 * While officially supported, packed YUV 4:2:2 formats can cause
+	 * random hardware crashes on JZ4725B, beyond repair, under certain
+	 * circumstances. It seems to happen with some specific resize ratios.
+	 * Until a proper workaround or fix is found, disable these formats.
 	DRM_FORMAT_YUYV,
 	DRM_FORMAT_YVYU,
 	DRM_FORMAT_UYVY,
 	DRM_FORMAT_VYUY,
+	*/
 	DRM_FORMAT_YUV411,
 	DRM_FORMAT_YUV420,
 	DRM_FORMAT_YUV422,
-- 
2.27.0