From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark yao Subject: Question: Re: [PATCH] drm/bridge: analogix: protect power when get_modes or detect Date: Wed, 12 Oct 2016 18:22:45 +0800 Message-ID: <57FE0EF5.7010207@rock-chips.com> References: <1476266442-29803-1-git-send-email-mark.yao@rock-chips.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0612561465==" Return-path: In-Reply-To: <1476266442-29803-1-git-send-email-mark.yao@rock-chips.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: David Airlie , Heiko Stuebner , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Gustavo Padovan List-Id: linux-rockchip.vger.kernel.org --===============0612561465== Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit

I'm not familiar with the analogix driver, maybe use a power reference count  would better then direct power on/off analogix_dp.

Does anyone has the idea to protect detect and get_modes context?

I found many other connector driver also direct access register on detect or get_modes, no problem for it?

On 2016年10月12日 18:00, Mark Yao wrote:
The drm callback ->detect and ->get_modes seems is not power safe,
they may be called when device is power off, do register access on
detect or get_modes will cause system die.

Here is the path call ->detect before analogix_dp power on
[<ffffff800843babc>] analogix_dp_detect+0x44/0xdc
[<ffffff80083fd840>] drm_helper_probe_single_connector_modes_merge_bits+0xe8/0x41c
[<ffffff80083fdb84>] drm_helper_probe_single_connector_modes+0x10/0x18
[<ffffff8008418d24>] drm_mode_getconnector+0xf4/0x304
[<ffffff800840cff0>] drm_ioctl+0x23c/0x390
[<ffffff80081a8adc>] do_vfs_ioctl+0x4b8/0x58c
[<ffffff80081a8c10>] SyS_ioctl+0x60/0x88

Cc: Inki Dae <inki.dae@samsung.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>

Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index efac8ab..09dece2 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1062,6 +1062,13 @@ int analogix_dp_get_modes(struct drm_connector *connector)
 		return 0;
 	}
 
+	if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+		pm_runtime_get_sync(dp->dev);
+
+		if (dp->plat_data->power_on)
+			dp->plat_data->power_on(dp->plat_data);
+	}
+
 	if (analogix_dp_handle_edid(dp) == 0) {
 		drm_mode_connector_update_edid_property(&dp->connector, edid);
 		num_modes += drm_add_edid_modes(&dp->connector, edid);
@@ -1073,6 +1080,13 @@ int analogix_dp_get_modes(struct drm_connector *connector)
 	if (dp->plat_data->get_modes)
 		num_modes += dp->plat_data->get_modes(dp->plat_data, connector);
 
+	if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+		if (dp->plat_data->power_off)
+			dp->plat_data->power_off(dp->plat_data);
+
+		pm_runtime_put_sync(dp->dev);
+	}
+
 	ret = analogix_dp_prepare_panel(dp, false, false);
 	if (ret)
 		DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
@@ -1106,9 +1120,23 @@ analogix_dp_detect(struct drm_connector *connector, bool force)
 		return connector_status_disconnected;
 	}
 
+	if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+		pm_runtime_get_sync(dp->dev);
+
+		if (dp->plat_data->power_on)
+			dp->plat_data->power_on(dp->plat_data);
+	}
+
 	if (!analogix_dp_detect_hpd(dp))
 		status = connector_status_connected;
 
+	if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+		if (dp->plat_data->power_off)
+			dp->plat_data->power_off(dp->plat_data);
+
+		pm_runtime_put_sync(dp->dev);
+	}
+
 	ret = analogix_dp_prepare_panel(dp, false, false);
 	if (ret)
 		DRM_ERROR("Failed to unprepare panel (%d)\n", ret);



-- 
Ｍark Yao
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