From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jae Hyun Yoo Date: Wed, 8 May 2019 15:19:52 -0700 Subject: [PATCH 1/7] media: aspeed: fix a kernel warning on clk control In-Reply-To: <1ec7397cb164b40877839bbc90f79b5942675fdb.camel@kernel.crashing.org> References: <20190502191317.29698-1-jae.hyun.yoo@linux.intel.com> <20190502191317.29698-2-jae.hyun.yoo@linux.intel.com> <1ec7397cb164b40877839bbc90f79b5942675fdb.camel@kernel.crashing.org> Message-ID: <6e93467e-1556-3cfd-b15c-c12b6907f526@linux.intel.com> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 5/7/2019 11:31 PM, Benjamin Herrenschmidt wrote: > On Thu, 2019-05-02 at 12:13 -0700, Jae Hyun Yoo wrote: >> Video engine clock control functions in the Aspeed video engine >> driver are being called from multiple context without any >> protection so video clocks can be double disabled and eventually >> it causes a kernel warning with stack dump printing out like below: > > I already objected to the use of set_bit, clear_bit etc... > > Either you are protected by a spinlock, in which case you don't need > them, use either the __ versions (non atomic) or just a bloody bool > flag which is a lot clearer and will generated better code. Or you > aren't protected in which case the code seems racy. Got it. I'll use __set_bit and __clear_bit instead. Thanks for your pointing it out. Regards, Jae >> [ 515.540498] ------------[ cut here ]------------ >> [ 515.545174] WARNING: CPU: 0 PID: 1310 at drivers/clk/clk.c:684 >> clk_core_unprepare+0x13c/0x170 >> [ 515.553806] vclk-gate already unprepared >> [ 515.557841] CPU: 0 PID: 1310 Comm: obmc-ikvm Tainted: >> G W 5.0.6-df66fbc97853fbba90a0bfa44de32f3d5f7602b4 #1 >> [ 515.568973] Hardware name: Generic DT based system >> [ 515.573777] Backtrace: >> [ 515.576272] [<80107cdc>] (dump_backtrace) from [<80107f10>] >> (show_stack+0x20/0x24) >> [ 515.583930] r7:803a5614 r6:00000009 r5:00000000 r4:9d88fe1c >> [ 515.589712] [<80107ef0>] (show_stack) from [<80690184>] >> (dump_stack+0x20/0x28) >> [ 515.597053] [<80690164>] (dump_stack) from [<80116044>] >> (__warn.part.3+0xb4/0xdc) >> [ 515.604557] [<80115f90>] (__warn.part.3) from [<801160d8>] >> (warn_slowpath_fmt+0x6c/0x90) >> [ 515.612734] r6:000002ac r5:8080befc r4:80a07008 >> [ 515.617463] [<80116070>] (warn_slowpath_fmt) from [<803a5614>] >> (clk_core_unprepare+0x13c/0x170) >> [ 515.626167] r3:8080cdf4 r2:8080bfc0 >> [ 515.629834] r7:98d682a8 r6:9d8a9200 r5:9e5151a0 r4:97abd620 >> [ 515.635530] [<803a54d8>] (clk_core_unprepare) from [<803a76a4>] >> (clk_unprepare+0x34/0x3c) >> [ 515.643812] r5:9e5151a0 r4:97abd620 >> [ 515.647529] [<803a7670>] (clk_unprepare) from [<804f36ec>] >> (aspeed_video_off+0x38/0x50) >> [ 515.655539] r5:9e5151a0 r4:9e504000 >> [ 515.659242] [<804f36b4>] (aspeed_video_off) from [<804f4358>] >> (aspeed_video_release+0x90/0x114) >> [ 515.668036] r5:9e5044b0 r4:9e504000 >> [ 515.671643] [<804f42c8>] (aspeed_video_release) from [<804d302c>] >> (v4l2_release+0xd4/0xe8) >> [ 515.679999] r7:98d682a8 r6:9d087810 r5:9d8a9200 r4:9e504318 >> [ 515.685695] [<804d2f58>] (v4l2_release) from [<80236454>] >> (__fput+0x98/0x1c4) >> [ 515.692914] r5:9e51b608 r4:9d8a9200 >> [ 515.696597] [<802363bc>] (__fput) from [<802365e8>] >> (____fput+0x18/0x1c) >> [ 515.703315] r9:80a0700c r8:801011e4 r7:00000000 r6:80a64b9c >> r5:9d8e35a0 r4:9d8e38dc >> [ 515.711167] [<802365d0>] (____fput) from [<80131ca4>] >> (task_work_run+0x7c/0xa0) >> [ 515.718596] [<80131c28>] (task_work_run) from [<80106884>] >> (do_work_pending+0x4a8/0x578) >> [ 515.726777] r7:801011e4 r6:80a07008 r5:9d88ffb0 r4:ffffe000 >> [ 515.732466] [<801063dc>] (do_work_pending) from [<8010106c>] >> (slow_work_pending+0xc/0x20) >> [ 515.740727] Exception stack(0x9d88ffb0 to 0x9d88fff8) >> [ 515.745840] ffa0: 00000000 >> 76f18094 00000000 00000000 >> [ 515.754122] ffc0: 00000007 00176778 7eda4c20 00000006 00000000 >> 00000000 48e20fa4 00000000 >> [ 515.762386] ffe0: 00000002 7eda4b08 00000000 48f91efc 80000010 >> 00000007 >> [ 515.769097] r10:00000000 r9:9d88e000 r8:801011e4 r7:00000006 >> r6:7eda4c20 r5:00176778 >> [ 515.777006] r4:00000007 >> [ 515.779558] ---[ end trace 12c04aadef8afbbb ]--- >> [ 515.784176] ------------[ cut here ]------------ >> [ 515.788817] WARNING: CPU: 0 PID: 1310 at drivers/clk/clk.c:825 >> clk_core_disable+0x18c/0x204 >> [ 515.797161] eclk-gate already disabled >> [ 515.800916] CPU: 0 PID: 1310 Comm: obmc-ikvm Tainted: >> G W 5.0.6-df66fbc97853fbba90a0bfa44de32f3d5f7602b4 #1 >> [ 515.811945] Hardware name: Generic DT based system >> [ 515.816730] Backtrace: >> [ 515.819210] [<80107cdc>] (dump_backtrace) from [<80107f10>] >> (show_stack+0x20/0x24) >> [ 515.826782] r7:803a5900 r6:00000009 r5:00000000 r4:9d88fe04 >> [ 515.832454] [<80107ef0>] (show_stack) from [<80690184>] >> (dump_stack+0x20/0x28) >> [ 515.839687] [<80690164>] (dump_stack) from [<80116044>] >> (__warn.part.3+0xb4/0xdc) >> [ 515.847170] [<80115f90>] (__warn.part.3) from [<801160d8>] >> (warn_slowpath_fmt+0x6c/0x90) >> [ 515.855247] r6:00000339 r5:8080befc r4:80a07008 >> [ 515.859868] [<80116070>] (warn_slowpath_fmt) from [<803a5900>] >> (clk_core_disable+0x18c/0x204) >> [ 515.868385] r3:8080cdd0 r2:8080c00c >> [ 515.871957] r7:98d682a8 r6:9d8a9200 r5:97abd560 r4:97abd560 >> [ 515.877615] [<803a5774>] (clk_core_disable) from [<803a59a0>] >> (clk_core_disable_lock+0x28/0x34) >> [ 515.886301] r7:98d682a8 r6:9d8a9200 r5:97abd560 r4:a0000013 >> [ 515.891960] [<803a5978>] (clk_core_disable_lock) from [<803a7714>] >> (clk_disable+0x2c/0x30) >> [ 515.900216] r5:9e5151a0 r4:9e515f60 >> [ 515.903816] [<803a76e8>] (clk_disable) from [<804f36f8>] >> (aspeed_video_off+0x44/0x50) >> [ 515.911656] [<804f36b4>] (aspeed_video_off) from [<804f4358>] >> (aspeed_video_release+0x90/0x114) >> [ 515.920341] r5:9e5044b0 r4:9e504000 >> [ 515.923921] [<804f42c8>] (aspeed_video_release) from [<804d302c>] >> (v4l2_release+0xd4/0xe8) >> [ 515.932184] r7:98d682a8 r6:9d087810 r5:9d8a9200 r4:9e504318 >> [ 515.937851] [<804d2f58>] (v4l2_release) from [<80236454>] >> (__fput+0x98/0x1c4) >> [ 515.944980] r5:9e51b608 r4:9d8a9200 >> [ 515.948559] [<802363bc>] (__fput) from [<802365e8>] >> (____fput+0x18/0x1c) >> [ 515.955257] r9:80a0700c r8:801011e4 r7:00000000 r6:80a64b9c >> r5:9d8e35a0 r4:9d8e38dc >> [ 515.963008] [<802365d0>] (____fput) from [<80131ca4>] >> (task_work_run+0x7c/0xa0) >> [ 515.970333] [<80131c28>] (task_work_run) from [<80106884>] >> (do_work_pending+0x4a8/0x578) >> [ 515.978421] r7:801011e4 r6:80a07008 r5:9d88ffb0 r4:ffffe000 >> [ 515.984086] [<801063dc>] (do_work_pending) from [<8010106c>] >> (slow_work_pending+0xc/0x20) >> [ 515.992247] Exception stack(0x9d88ffb0 to 0x9d88fff8) >> [ 515.997296] ffa0: 00000000 >> 76f18094 00000000 00000000 >> [ 516.005473] ffc0: 00000007 00176778 7eda4c20 00000006 00000000 >> 00000000 48e20fa4 00000000 >> [ 516.013642] ffe0: 00000002 7eda4b08 00000000 48f91efc 80000010 >> 00000007 >> [ 516.020257] r10:00000000 r9:9d88e000 r8:801011e4 r7:00000006 >> r6:7eda4c20 r5:00176778 >> [ 516.028072] r4:00000007 >> [ 516.030606] ---[ end trace 12c04aadef8afbbc ]--- >> >> To prevent this issue, this commit adds spinlock protection and >> clock status checking logic into the Aspeed video engine driver. >> >> Signed-off-by: Jae Hyun Yoo >> Reviewed-by: Eddie James >> --- >> drivers/media/platform/aspeed-video.c | 32 ++++++++++++++++++++++++- >> -- >> 1 file changed, 29 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/media/platform/aspeed-video.c >> b/drivers/media/platform/aspeed-video.c >> index 55c55a68b016..2dac6d20b180 100644 >> --- a/drivers/media/platform/aspeed-video.c >> +++ b/drivers/media/platform/aspeed-video.c >> @@ -187,6 +187,7 @@ enum { >> VIDEO_STREAMING, >> VIDEO_FRAME_INPRG, >> VIDEO_STOPPED, >> + VIDEO_CLOCKS_ON, >> }; >> >> struct aspeed_video_addr { >> @@ -483,19 +484,29 @@ static void >> aspeed_video_enable_mode_detect(struct aspeed_video *video) >> >> static void aspeed_video_off(struct aspeed_video *video) >> { >> + if (!test_bit(VIDEO_CLOCKS_ON, &video->flags)) >> + return; >> + >> /* Disable interrupts */ >> aspeed_video_write(video, VE_INTERRUPT_CTRL, 0); >> >> /* Turn off the relevant clocks */ >> clk_disable_unprepare(video->vclk); >> clk_disable_unprepare(video->eclk); >> + >> + clear_bit(VIDEO_CLOCKS_ON, &video->flags); >> } >> >> static void aspeed_video_on(struct aspeed_video *video) >> { >> + if (test_bit(VIDEO_CLOCKS_ON, &video->flags)) >> + return; >> + >> /* Turn on the relevant clocks */ >> clk_prepare_enable(video->eclk); >> clk_prepare_enable(video->vclk); >> + >> + set_bit(VIDEO_CLOCKS_ON, &video->flags); >> } >> >> static void aspeed_video_bufs_done(struct aspeed_video *video, >> @@ -513,12 +524,14 @@ static void aspeed_video_bufs_done(struct >> aspeed_video *video, >> >> static void aspeed_video_irq_res_change(struct aspeed_video *video) >> { >> + spin_lock(&video->lock); >> dev_dbg(video->dev, "Resolution changed; resetting\n"); >> >> set_bit(VIDEO_RES_CHANGE, &video->flags); >> clear_bit(VIDEO_FRAME_INPRG, &video->flags); >> >> aspeed_video_off(video); >> + spin_unlock(&video->lock); >> aspeed_video_bufs_done(video, VB2_BUF_STATE_ERROR); >> >> schedule_delayed_work(&video->res_work, >> RESOLUTION_CHANGE_DELAY); >> @@ -938,9 +951,13 @@ static void aspeed_video_init_regs(struct >> aspeed_video *video) >> >> static void aspeed_video_start(struct aspeed_video *video) >> { >> + unsigned long flags; >> + >> + spin_lock_irqsave(&video->lock, flags); >> aspeed_video_on(video); >> >> aspeed_video_init_regs(video); >> + spin_unlock_irqrestore(&video->lock, flags); >> >> /* Resolution set to 640x480 if no signal found */ >> aspeed_video_get_resolution(video); >> @@ -956,6 +973,9 @@ static void aspeed_video_start(struct >> aspeed_video *video) >> >> static void aspeed_video_stop(struct aspeed_video *video) >> { >> + unsigned long flags; >> + >> + spin_lock_irqsave(&video->lock, flags); >> set_bit(VIDEO_STOPPED, &video->flags); >> cancel_delayed_work_sync(&video->res_work); >> >> @@ -969,6 +989,7 @@ static void aspeed_video_stop(struct aspeed_video >> *video) >> >> video->v4l2_input_status = V4L2_IN_ST_NO_SIGNAL; >> video->flags = 0; >> + spin_unlock_irqrestore(&video->lock, flags); >> } >> >> static int aspeed_video_querycap(struct file *file, void *fh, >> @@ -1306,16 +1327,21 @@ static void >> aspeed_video_resolution_work(struct work_struct *work) >> struct delayed_work *dwork = to_delayed_work(work); >> struct aspeed_video *video = container_of(dwork, struct >> aspeed_video, >> res_work); >> - u32 input_status = video->v4l2_input_status; >> + unsigned long flags; >> + u32 input_status; >> >> + spin_lock_irqsave(&video->lock, flags); >> + input_status = video->v4l2_input_status; >> aspeed_video_on(video); >> >> /* Exit early in case no clients remain */ >> - if (test_bit(VIDEO_STOPPED, &video->flags)) >> + if (test_bit(VIDEO_STOPPED, &video->flags)) { >> + spin_unlock_irqrestore(&video->lock, flags); >> goto done; >> + } >> >> aspeed_video_init_regs(video); >> - >> + spin_unlock_irqrestore(&video->lock, flags); >> aspeed_video_get_resolution(video); >> >> if (video->detected_timings.width != video- >>> active_timings.width || >