Before the drm driver had support for this file there was a driver that exposed the contents of the vga password register to userspace. It would present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining why. This breaks the existing userspace, which is looking for 0xa8 in the lower byte.
Change our implementation to expose the entire register.
Fixes: 696029eb36c0 ("drm/aspeed: Add sysfs for output settings") Reported-by: Oskar Senft osk@google.com Signed-off-by: Joel Stanley joel@jms.id.au --- drivers/gpu/drm/aspeed/aspeed_gfx_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c index b53fee6f1c17..65f172807a0d 100644 --- a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c +++ b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c @@ -291,7 +291,7 @@ vga_pw_show(struct device *dev, struct device_attribute *attr, char *buf) if (rc) return rc;
- return sprintf(buf, "%u\n", reg & 1); + return sprintf(buf, "%u\n", reg); } static DEVICE_ATTR_RO(vga_pw);
On Tue, Nov 16, 2021 at 8:02 PM Joel Stanley joel@jms.id.au wrote:
Before the drm driver had support for this file there was a driver that exposed the contents of the vga password register to userspace. It would present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining why. This breaks the existing userspace, which is looking for 0xa8 in the lower byte.
Change our implementation to expose the entire register.
Fixes: 696029eb36c0 ("drm/aspeed: Add sysfs for output settings") Reported-by: Oskar Senft osk@google.com Signed-off-by: Joel Stanley joel@jms.id.au
drivers/gpu/drm/aspeed/aspeed_gfx_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c index b53fee6f1c17..65f172807a0d 100644 --- a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c +++ b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c @@ -291,7 +291,7 @@ vga_pw_show(struct device *dev, struct device_attribute *attr, char *buf) if (rc) return rc;
return sprintf(buf, "%u\n", reg & 1);
return sprintf(buf, "%u\n", reg);} static DEVICE_ATTR_RO(vga_pw);
-- 2.33.0
Tested-by: Oskar Senft osk@google.com
Hi Joel,
Before the drm driver had support for this file there was a driver that exposed the contents of the vga password register to userspace. It would present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining why. This breaks the existing userspace, which is looking for 0xa8 in the lower byte.
Change our implementation to expose the entire register.
As a userspace consumer of this:
Reviewed-by: Jeremy Kerr jk@codeconstruct.com.au
Thanks!
Jeremy
Hi David, Daniel,
On Fri, 19 Nov 2021 at 06:54, Jeremy Kerr jk@codeconstruct.com.au wrote:
Hi Joel,
Before the drm driver had support for this file there was a driver that exposed the contents of the vga password register to userspace. It would present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining why. This breaks the existing userspace, which is looking for 0xa8 in the lower byte.
Change our implementation to expose the entire register.
As a userspace consumer of this:
Reviewed-by: Jeremy Kerr jk@codeconstruct.com.au
Am I okay to apply this to drm-misc-fixes? I've not applied a patch to the fixes tree before, so I wanted to check if there is some process I've missed.
Cheers,
Joel
On Wed, 17 Nov 2021 09:01:45 +0800, Joel Stanley wrote:
Before the drm driver had support for this file there was a driver that exposed the contents of the vga password register to userspace. It would present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining why. This breaks the existing userspace, which is looking for 0xa8 in the lower byte.
[...]
Applied to drm/drm-misc (drm-misc-fixes).
Thanks! Maxime
dri-devel@lists.freedesktop.org
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Jeremy Kerr -
Joel Stanley -
Maxime Ripard -
Oskar Senft