Re: [PATCH] omapfb: In omapfb_probe return -EPROBE_DEFER when display driver is not loaded yet
From: Pali Rohár <hidden>
Date: 2013-08-05 06:45:58
Also in:
linux-omap, lkml
Hello, On Tuesday 23 July 2013 12:01:39 Tomi Valkeinen wrote:
On 13/07/13 21:27, Pavel Machek wrote:quoted
On Wed 2013-07-10 15:08:59, Pali Rohár wrote:quoted
* On RX-51 probing for acx565akm driver is later then for omapfb which cause that omapfb probe fail and framebuffer is not working * EPROBE_DEFER causing that kernel try to probe for omapfb later again which fixing this problem * Without this patch display on Nokia RX-51 (N900) phone not working Signed-off-by: Pali Rohár <redacted>Tested-by: Pavel Machek <redacted>Which kernel version is this? Does it have dfbc32316c6991010328c21e6046b05bac57eb84 (OMAPFB: defer probe if no displays)?
Kernel 3.10, so it have above commit.
Then again, rx51 has tv-output, which probably gets probed early. So omapfb does see one functional display, and starts, even if the LCD is not available yet.quoted
(Actually, do we know which commit broke the ordering? We may want to simply revert that one...)Well, my understand that this is how it's supposed to work. There's no defined order with the driver probes, and the drivers just have to deal with their dependencies not being there yet. I don't have a perfect solution for this problem for omapfb. omapfb doesn't support dynamically adding displays, so all the displays it uses have to be probed before omapfb. And omapfb doesn't know which displays will be probed. The patch below was added for 3.11. Does it fix the issue for you? Perhaps it should be added for 3.10 also. Tomi
I tested patch below and it fixing our problem too. So it could be added to 3.10.
quoted hunk ↗ jump to hunk
commit e9f322b4913e5d3e5c5d21dc462ca6f8a86e1df1 Author: Tomi Valkeinen [off-list ref] Date: Thu May 23 16:41:25 2013 +0300 OMAPFB: use EPROBE_DEFER if default display is not present Currently omapfb returns EPROBE_DEFER if no displays have been probed at the time omapfb is probed. However, sometimes some of the displays have been probed at that time, but not all. We can't return EPROBE_DEFER in that case, because then one missing driver would cause omapfb to defer always, preventing any display from working. However, if the user has defined a default display, we can presume that the driver for that display is eventually loaded. Thus, this patch changes omapfb to return EPROBE_DEFER in case default display is not found. Signed-off-by: Tomi Valkeinen [off-list ref]diff --git a/drivers/video/omap2/omapfb/omapfb-main.cb/drivers/video/omap2/omapfb/omapfb-main.c index 528e453..27d6905 100644--- a/drivers/video/omap2/omapfb/omapfb-main.c +++ b/drivers/video/omap2/omapfb/omapfb-main.c@@ -2503,7 +2503,7 @@ static int omapfb_probe(structplatform_device *pdev) if (def_display == NULL) { dev_err(fbdev->dev, "failed to find default display\n"); - r = -EINVAL; + r = -EPROBE_DEFER; goto cleanup; }
-- Pali Rohár pali.rohar@gmail.com
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