From mboxrd@z Thu Jan 1 00:00:00 1970 From: Archit Taneja Subject: [PATCH v3 2/7] drm/i2c: adv7511: Fix mutex deadlock when interrupts are disabled Date: Wed, 9 Mar 2016 16:27:13 +0530 Message-ID: <1457521038-5906-3-git-send-email-architt@codeaurora.org> References: <1441625800-1858-1-git-send-email-architt@codeaurora.org> <1457521038-5906-1-git-send-email-architt@codeaurora.org> Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:59708 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752325AbcCIK5f (ORCPT ); Wed, 9 Mar 2016 05:57:35 -0500 In-Reply-To: <1457521038-5906-1-git-send-email-architt@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: dri-devel@lists.freedesktop.org Cc: airlied@linux.ie, daniel@ffwll.ch, treding@nvidia.com, linux-arm-msm@vger.kernel.org, srinivas.kandagatla@linaro.org, andy.green@linaro.org, laurent.pinchart@ideasonboard.com, lars@metafoo.de, xinliang.liu@linaro.org, amit.kucheria@linaro.org, robdclark@gmail.com, Archit Taneja 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 --- drivers/gpu/drm/i2c/adv7511.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i2c/adv7511.c b/drivers/gpu/drm/i2c/adv7511.c index fec5627..c00d11d 100644 --- a/drivers/gpu/drm/i2c/adv7511.c +++ b/drivers/gpu/drm/i2c/adv7511.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; -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation