Re: [PATCH] drm/bochs: add edid present check

From: Oleksandr Andrushchenko
Date: Wed Dec 19 2018 - 09:10:22 EST

Hello, Gerd!

On 12/18/18 9:33 AM, Gerd Hoffmann wrote:
Check first two header bytes before trying to read the edid blob,
to avoid the log being spammed in case qemu has no edid support (old
qemu or edid turned off).

Fixes: 01f23459cf drm/bochs: add edid support.
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
drivers/gpu/drm/bochs/bochs_hw.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/bochs/bochs_hw.c b/drivers/gpu/drm/bochs/bochs_hw.c
index c90a0d492f..f91e049625 100644
--- a/drivers/gpu/drm/bochs/bochs_hw.c
+++ b/drivers/gpu/drm/bochs/bochs_hw.c
@@ -89,6 +89,10 @@ int bochs_hw_load_edid(struct bochs_device *bochs)
if (!bochs->mmio)
return -1;

You could probably have a comment here explaining the magic below

(just like in the commit message to ease the task of understanding

while reading the code why 2 of 8 bytes of the EDID header is checked

and why it is all needed). Of course one can use git blame... Up to you

+ if (readb(bochs->mmio + 0) != 0x00 ||
+ readb(bochs->mmio + 1) != 0xff)

bochs->mmio is defined as "void __iomemÂÂ *mmio;". Can we please avoid

void pointer arithmetic here?

+ return -1;
bochs->edid = drm_do_get_edid(&bochs->connector,
bochs_get_edid_block, bochs);

With the above fixed:

Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>