On 2022-06-14 14:48, Thomas Zimmermann wrote:
Hi
Am 14.06.22 um 15:04 schrieb Robin Murphy:
The Arm Juno board EDK2 port has provided an EFI GOP display via HDLCD0
for some time now, which works nicely as an early framebuffer. However,
once the HDLCD driver probes and takes over the hardware, it should
take over the logical framebuffer as well, otherwise the now-defunct GOP
device hangs about and virtual console output inevitably disappears into
the wrong place most of the time.
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
drivers/gpu/drm/arm/hdlcd_drv.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c
b/drivers/gpu/drm/arm/hdlcd_drv.c
index af59077a5481..a5d04884658b 100644
--- a/drivers/gpu/drm/arm/hdlcd_drv.c
+++ b/drivers/gpu/drm/arm/hdlcd_drv.c
@@ -331,6 +331,8 @@ static int hdlcd_drm_bind(struct device *dev)
goto err_vblank;
}
+ drm_fb_helper_remove_conflicting_framebuffers(NULL, "hdlcd", false);
+
In addition to what Javier said, it appears to be too late to call this
function. If anything her etouches hardware, you might accidentally
interfere with the EFI-related driver. Rather call it at the top of
ldlcd_drm_bind().
OK, thanks for the info. I mostly just copied the pattern from the
simplest-looking other users (sun4i, tegra, vc4) who all seemed to call
it fairly late, and indeed naively it seemed logical not to do it *too*
early when there's more chance we might fail to bind and leave the user
with no framebuffer at all. In particular, waiting until we've bound the
HDMI encoder seems like a good idea in the case of the Juno board (which
is the only real HDLCD user), as the I2C bus often gets stuck if the
System Control Processor is having a bad day. I also don't believe
there's anything here that would affect efifb more than the fact that
once the DRM CRTC is alive we simply stop scanning out from the region
of memory that efifb is managing, but if it's considered good practice
to do this early then I can certainly make that change too.
Cheers,
Robin.
