On 11/21/2017 01:19 PM, Marek Szyprowski wrote:
get_modes() callback might be called asynchronously from the DRM core and it is not synchronized with bridge_enable(), which sets proper runtime PM state of the main DP device. Fix this by calling pm_runtime_get_sync() before calling drm_get_edid(), which in turn calls drm_dp_i2c_xfer() and analogix_dp_transfer() to ensure that main DP device is runtime active when doing any access to its registers.
Looks good to me. Would be nice to get an ack from rockchip too. Will queue it to drm-misc-fixes (so that it's merged for 4.15-rc2) if no one has any objections. Thanks, Archit
This fixes the following kernel issue on Samsung Exynos5250 Snow board: Unhandled fault: imprecise external abort (0x406) at 0x00000000 pgd = c0004000 [00000000] *pgd=00000000 Internal error: : 406 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 62 Comm: kworker/0:2 Not tainted 4.13.0-rc2-00364-g4a97a3da420b #3357 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) Workqueue: events output_poll_execute task: edc14800 task.stack: edcb2000 PC is at analogix_dp_transfer+0x15c/0x2fc LR is at analogix_dp_transfer+0x134/0x2fc pc : [<c0468538>] lr : [<c0468510>] psr: 60000013 sp : edcb3be8 ip : 0000002a fp : 00000001 r10: 00000000 r9 : edcb3cd8 r8 : edcb3c40 r7 : 00000000 r6 : edd3b380 r5 : edd3b010 r4 : 00000064 r3 : 00000000 r2 : f0ad3000 r1 : edcb3c40 r0 : edd3b010 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 4000406a DAC: 00000051 Process kworker/0:2 (pid: 62, stack limit = 0xedcb2210) Stack: (0xedcb3be8 to 0xedcb4000) [<c0468538>] (analogix_dp_transfer) from [<c0424ba4>] (drm_dp_i2c_do_msg+0x8c/0x2b4) [<c0424ba4>] (drm_dp_i2c_do_msg) from [<c0424e64>] (drm_dp_i2c_xfer+0x98/0x214) [<c0424e64>] (drm_dp_i2c_xfer) from [<c057b2d8>] (__i2c_transfer+0x140/0x29c) [<c057b2d8>] (__i2c_transfer) from [<c057b4a4>] (i2c_transfer+0x70/0xe4) [<c057b4a4>] (i2c_transfer) from [<c0441de4>] (drm_do_probe_ddc_edid+0xb4/0x114) [<c0441de4>] (drm_do_probe_ddc_edid) from [<c0441e5c>] (drm_probe_ddc+0x18/0x28) [<c0441e5c>] (drm_probe_ddc) from [<c0445728>] (drm_get_edid+0x124/0x2d4) [<c0445728>] (drm_get_edid) from [<c0465ea0>] (analogix_dp_get_modes+0x90/0x114) [<c0465ea0>] (analogix_dp_get_modes) from [<c0425e8c>] (drm_helper_probe_single_connector_modes+0x198/0x68c) [<c0425e8c>] (drm_helper_probe_single_connector_modes) from [<c04325d4>] (drm_setup_crtcs+0x1b4/0xd18) [<c04325d4>] (drm_setup_crtcs) from [<c04344a8>] (drm_fb_helper_hotplug_event+0x94/0xd0) [<c04344a8>] (drm_fb_helper_hotplug_event) from [<c0425a50>] (drm_kms_helper_hotplug_event+0x24/0x28) [<c0425a50>] (drm_kms_helper_hotplug_event) from [<c04263ec>] (output_poll_execute+0x6c/0x174) [<c04263ec>] (output_poll_execute) from [<c0136f18>] (process_one_work+0x188/0x3fc) [<c0136f18>] (process_one_work) from [<c01371f4>] (worker_thread+0x30/0x4b8) [<c01371f4>] (worker_thread) from [<c013daf8>] (kthread+0x128/0x164) [<c013daf8>] (kthread) from [<c0108510>] (ret_from_fork+0x14/0x24) Code: 0a000002 ea000009 e2544001 0a00004a (e59537c8) ---[ end trace cddc7919c79f7878 ]--- Reported-by: Misha Komarovskiy <zombah@xxxxxxxxx> CC: stable@xxxxxxxxxxxxxxx # v4.10+ Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> --- This issue was there from the beginning, but recent changes to DRM core revealed it. It makes sense to backport it to patch f0a8b49c03d2 ("drm/bridge: analogix dp: Fix runtime PM state on driver bind"), which fixed similar issue on driver bind, thus I've marked it for stable v4.10+. Best regards Marek Szyprowski Samsung R&D Institute Poland --- drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index 5dd3f1cd074a..a8905049b9da 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -946,7 +946,9 @@ static int analogix_dp_get_modes(struct drm_connector *connector) return 0; }+ pm_runtime_get_sync(dp->dev);edid = drm_get_edid(connector, &dp->aux.ddc); + pm_runtime_put(dp->dev); if (edid) { drm_mode_connector_update_edid_property(&dp->connector, edid);
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