When the adv7511 i2c client doesn't have an interrupt line, we observe a deadlock on caused by trying to lock drm device's mode_config.mutex twice in the same context.
Here is the sequence that causes it:
ioctl DRM_IOCTL_MODE_GETCONNECTOR from userspace drm_mode_getconnector (acquires mode_config mutex) connector->fill_modes() drm_helper_probe_single_connector_modes connector_funcs->get_modes adv7511_encoder_get_modes adv7511_get_edid_block adv7511_irq_process drm_helper_hpd_irq_event (acquires mode_config mutex again)
In adv7511_irq_process, don't call drm_helper_hpd_irq_event when not called from the interrupt handler. It doesn't serve any purpose there anyway.
Signed-off-by: Archit Taneja architt@codeaurora.org --- drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c index c2642f9..1fff0ab 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c @@ -427,7 +427,7 @@ static bool adv7511_hpd(struct adv7511 *adv7511) return false; }
-static int adv7511_irq_process(struct adv7511 *adv7511) +static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd) { unsigned int irq0, irq1; int ret; @@ -443,7 +443,7 @@ static int adv7511_irq_process(struct adv7511 *adv7511) regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0); regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);
- if (irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder) + if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder) drm_helper_hpd_irq_event(adv7511->connector.dev);
if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) { @@ -461,7 +461,7 @@ static irqreturn_t adv7511_irq_handler(int irq, void *devid) struct adv7511 *adv7511 = devid; int ret;
- ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, true); return ret < 0 ? IRQ_NONE : IRQ_HANDLED; }
@@ -478,7 +478,7 @@ static int adv7511_wait_for_edid(struct adv7511 *adv7511, int timeout) adv7511->edid_read, msecs_to_jiffies(timeout)); } else { for (; timeout > 0; timeout -= 25) { - ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, false); if (ret < 0) break;