Re: [PATCH 1/4] HID: picolcd: fix deferred_io init/cleanup to
From: Jaya Kumar <hidden>
Date: 2010-06-30 01:52:19
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On Tue, Jun 29, 2010 at 4:29 AM, Bruno Prémont [off-list ref] wrote:
We need to call fb_deferred_io_init() before we register_framebuffer() as otherwise, in case fbcon uses our framebuffer, we will get a BUG() because in picolcd_fb_imageblit() we schedule defio which has not been initialized yet.
Hi Bruno, The comment above seems confusing to me in that it talks about fbcon and defio schedule. What I see is that you originally had in picolcd:
error = register_framebuffer(info);
...
fb_deferred_io_init(info);
which was a bug because it called register_framebuffer (ie: made the framebuffer available for use) and only then initialized the defio handlers which were needed for that framebuffer memory to be used. Drivers must always call defio_init _before_ register_framebuffer. The bug fix to picolcd below looks correct because it now does that sequence in the correct order. Thanks, jaya
quoted hunk ↗ jump to hunk
Note: this BUG() deadlocks ttys. Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org> --- drivers/hid/hid-picolcd.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c index 95253b3..883d720 100644 --- a/drivers/hid/hid-picolcd.c +++ b/drivers/hid/hid-picolcd.c@@ -707,18 +707,19 @@ static int picolcd_init_framebuffer(struct picolcd_data *data)dev_err(dev, "failed to create sysfs attributes\n"); goto err_cleanup; } + fb_deferred_io_init(info); data->fb_info = info; error = register_framebuffer(info); if (error) { dev_err(dev, "failed to register framebuffer\n"); goto err_sysfs; } - fb_deferred_io_init(info); /* schedule first output of framebuffer */ schedule_delayed_work(&info->deferred_work, 0); return 0; err_sysfs: + fb_deferred_io_cleanup(info); device_remove_file(dev, &dev_attr_fb_update_rate); err_cleanup: data->fb_vbitmap = NULL;@@ -747,7 +748,6 @@ static void picolcd_exit_framebuffer(struct picolcd_data *data)data->fb_bpp = 0; data->fb_info = NULL; device_remove_file(&data->hdev->dev, &dev_attr_fb_update_rate); - fb_deferred_io_cleanup(info); unregister_framebuffer(info); vfree(fb_bitmap); kfree(fb_vbitmap); -- 1.7.1