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Groups > linux.kernel > #1586583 > unrolled thread
| Started by | John Stultz <john.stultz@linaro.org> |
|---|---|
| First post | 2017-02-23 02:00 +0100 |
| Last post | 2017-02-25 02:30 +0100 |
| Articles | 4 — 2 participants |
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[RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race John Stultz <john.stultz@linaro.org> - 2017-02-23 02:00 +0100
Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race liuxinliang <z.liuxinliang@hisilicon.com> - 2017-02-24 03:00 +0100
Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race John Stultz <john.stultz@linaro.org> - 2017-02-24 22:40 +0100
Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race liuxinliang <z.liuxinliang@hisilicon.com> - 2017-02-25 02:30 +0100
| From | John Stultz <john.stultz@linaro.org> |
|---|---|
| Date | 2017-02-23 02:00 +0100 |
| Subject | [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race |
| Message-ID | <tdPVf-1JC-1@gated-at.bofh.it> |
In some cases I've been seeing a race where two framebuffers
would be initialized, as kirin_fbdev_output_poll_changed()
might get called quickly in succession, resulting in the fb
initialization happening twice. This could cause the system
to boot up with a blank screen.
This patch adds a simple mutex to serialize it and seems to
avoid the race.
Obviously I suspect this patch isn't the best solution, but
I wanted to send it out as something concrete to discuss the
bug.
Suggestions or feedback for a better solution would be greatly
appreciated.
Cc: Xinliang Liu <z.liuxinliang@hisilicon.com>
Cc: Rongrong Zou <zourongrong@gmail.com>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Chen Feng <puck.chen@hisilicon.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
index ebd5f4f..80c607f 100644
--- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
@@ -50,11 +50,13 @@ static int kirin_drm_kms_cleanup(struct drm_device *dev)
return 0;
}
+static DEFINE_MUTEX(fb_lock);
#ifdef CONFIG_DRM_FBDEV_EMULATION
static void kirin_fbdev_output_poll_changed(struct drm_device *dev)
{
struct kirin_drm_private *priv = dev->dev_private;
+ mutex_lock(&fb_lock);
if (priv->fbdev) {
drm_fbdev_cma_hotplug_event(priv->fbdev);
} else {
@@ -64,6 +66,7 @@ static void kirin_fbdev_output_poll_changed(struct drm_device *dev)
if (IS_ERR(priv->fbdev))
priv->fbdev = NULL;
}
+ mutex_unlock(&fb_lock);
}
#endif
--
2.7.4
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| From | liuxinliang <z.liuxinliang@hisilicon.com> |
|---|---|
| Date | 2017-02-24 03:00 +0100 |
| Subject | Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race |
| Message-ID | <tedkR-1ou-7@gated-at.bofh.it> |
| In reply to | #1586583 |
Hi John,
On 2017/2/23 8:56, John Stultz wrote:
> In some cases I've been seeing a race where two framebuffers
> would be initialized, as kirin_fbdev_output_poll_changed()
> might get called quickly in succession, resulting in the fb
> initialization happening twice. This could cause the system
I might understand this race. This because two places call
drm_helper_hpd_irq_event might cause the race:
One place is here
static int kirin_drm_kms_init(struct drm_device *dev)
{
...
/* force detection after connectors init */
(void)drm_helper_hpd_irq_event(dev);
...
}
another is the adv7533 interrupt thread handler
static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
{
...
if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
drm_helper_hpd_irq_event(adv7511->connector.dev);
...
}
right?
I don't get a better way to fix this yet , I like to put fb_lock into
kirin_drm_private.
And it seems hard to fix this in the core drm_helper_hpd_irq_event.
-xinliang
> to boot up with a blank screen.
>
> This patch adds a simple mutex to serialize it and seems to
> avoid the race.
>
> Obviously I suspect this patch isn't the best solution, but
> I wanted to send it out as something concrete to discuss the
> bug.
>
> Suggestions or feedback for a better solution would be greatly
> appreciated.
>
> Cc: Xinliang Liu <z.liuxinliang@hisilicon.com>
> Cc: Rongrong Zou <zourongrong@gmail.com>
> Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
> Cc: Chen Feng <puck.chen@hisilicon.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Sean Paul <seanpaul@chromium.org>
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
> index ebd5f4f..80c607f 100644
> --- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
> +++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c
> @@ -50,11 +50,13 @@ static int kirin_drm_kms_cleanup(struct drm_device *dev)
> return 0;
> }
>
> +static DEFINE_MUTEX(fb_lock);
> #ifdef CONFIG_DRM_FBDEV_EMULATION
> static void kirin_fbdev_output_poll_changed(struct drm_device *dev)
> {
> struct kirin_drm_private *priv = dev->dev_private;
>
> + mutex_lock(&fb_lock);
> if (priv->fbdev) {
> drm_fbdev_cma_hotplug_event(priv->fbdev);
> } else {
> @@ -64,6 +66,7 @@ static void kirin_fbdev_output_poll_changed(struct drm_device *dev)
> if (IS_ERR(priv->fbdev))
> priv->fbdev = NULL;
> }
> + mutex_unlock(&fb_lock);
> }
> #endif
>
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| From | John Stultz <john.stultz@linaro.org> |
|---|---|
| Date | 2017-02-24 22:40 +0100 |
| Message-ID | <tevKN-693-7@gated-at.bofh.it> |
| In reply to | #1587238 |
On Thu, Feb 23, 2017 at 5:55 PM, liuxinliang
<z.liuxinliang@hisilicon.com> wrote:
> Hi John,
>
> On 2017/2/23 8:56, John Stultz wrote:
>>
>> In some cases I've been seeing a race where two framebuffers
>> would be initialized, as kirin_fbdev_output_poll_changed()
>> might get called quickly in succession, resulting in the fb
>> initialization happening twice. This could cause the system
>
>
> I might understand this race. This because two places call
> drm_helper_hpd_irq_event might cause the race:
> One place is here
> static int kirin_drm_kms_init(struct drm_device *dev)
> {
> ...
> /* force detection after connectors init */
> (void)drm_helper_hpd_irq_event(dev);
> ...
> }
>
> another is the adv7533 interrupt thread handler
> static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
> {
> ...
> if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
> drm_helper_hpd_irq_event(adv7511->connector.dev);
> ...
> }
>
> right?
>
> I don't get a better way to fix this yet , I like to put fb_lock into
> kirin_drm_private.
Ok. I've moved the mutex to the kirin_drm_private structure.
Anything else you'd like to see before I resend?
thanks
-john
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| From | liuxinliang <z.liuxinliang@hisilicon.com> |
|---|---|
| Date | 2017-02-25 02:30 +0100 |
| Subject | Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race |
| Message-ID | <tezlo-mo-7@gated-at.bofh.it> |
| In reply to | #1587951 |
On 2017/2/25 5:33, John Stultz wrote:
> On Thu, Feb 23, 2017 at 5:55 PM, liuxinliang
> <z.liuxinliang@hisilicon.com> wrote:
>> Hi John,
>>
>> On 2017/2/23 8:56, John Stultz wrote:
>>> In some cases I've been seeing a race where two framebuffers
>>> would be initialized, as kirin_fbdev_output_poll_changed()
>>> might get called quickly in succession, resulting in the fb
>>> initialization happening twice. This could cause the system
>>
>> I might understand this race. This because two places call
>> drm_helper_hpd_irq_event might cause the race:
>> One place is here
>> static int kirin_drm_kms_init(struct drm_device *dev)
>> {
>> ...
>> /* force detection after connectors init */
>> (void)drm_helper_hpd_irq_event(dev);
>> ...
>> }
>>
>> another is the adv7533 interrupt thread handler
>> static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
>> {
>> ...
>> if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
>> drm_helper_hpd_irq_event(adv7511->connector.dev);
>> ...
>> }
>>
>> right?
>>
>> I don't get a better way to fix this yet , I like to put fb_lock into
>> kirin_drm_private.
> Ok. I've moved the mutex to the kirin_drm_private structure.
>
> Anything else you'd like to see before I resend?
Thanks, no more then.
Best,
-xinliang
>
> thanks
> -john
>
> .
>
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