On Tue, Nov 04, 2014 at 11:59:46AM +0100, Andrzej Hajda wrote:
Hi Thierry,
Just passing by.
On 11/03/2014 10:27 AM, Thierry Reding wrote:
From: Thierry Reding treding@nvidia.com
The HDMI hotplug signal may toggle after the DRM driver has been unloaded. Make sure not to call into DRM if that's the case.
Signed-off-by: Thierry Reding treding@nvidia.com
drivers/gpu/drm/tegra/output.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c index 6b393cfbb5e7..def74914dd72 100644 --- a/drivers/gpu/drm/tegra/output.c +++ b/drivers/gpu/drm/tegra/output.c @@ -181,7 +181,8 @@ static irqreturn_t hpd_irq(int irq, void *data) { struct tegra_output *output = data;
- drm_helper_hpd_irq_event(output->connector.dev);
if (output->connector.dev)
drm_helper_hpd_irq_event(output->connector.dev);return IRQ_HANDLED;
}
Since output->connector.dev is not synchronized between irq and other code this patch do not solves the issue, it just decreases chances of the disaster.
You're right. I guess in addition to this we could call enable_irq() when the connector is bound to the DRM device and disable_irq() when it is unbound. Actually, that should even allow drm_helper_hpd_irq_event() to be called unconditionally because .dev could not be NULL in that case.
Upon closer inspection it seems like the majority of drivers would fall prey to this particular race.
Thierry