Messages in this thread | | | Date | Wed, 30 Jun 2010 07:56:57 +0200 | From | Bruno Prémont <> | Subject | Re: [PATCH 1/4] HID: picolcd: fix deferred_io init/cleanup to (un)register_framebuffer ordering |
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Hi Jaya,
On Wed, 30 Jun 2010 09:52:13 Jaya Kumar wrote: > On Tue, Jun 29, 2010 at 4:29 AM, Bruno Prémont > <bonbons@linux-vserver.org> 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.
Well I talk about fbcon as that's the trigger I have seen causing an issue.
I'm fine with rewriting the changelog as to just talk about the correct/expected order of initialization.
Thanks for looking at it, Bruno
> 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 > > > > > > > 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 > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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