On Thu, Jun 30, 2011 at 1:37 AM, Paul Walmsley <paul@xxxxxxxxx> wrote: > cc'ing lakml > > Hi Venkat, Balaji, > > On Wed, 29 Jun 2011, S, Venkatraman wrote: > >> On Wed, Jun 29, 2011 at 9:08 PM, Paul Walmsley <paul@xxxxxxxxx> wrote: >> > On Wed, 29 Jun 2011, T Krishnamoorthy, Balaji wrote: >> > >> >> There have been some experiments on our customer programs to reduce this >> >> value to a few ms and infrequent crashes were observed (stress testing >> >> for several hours) while trying to access the controller registers. >> > >> > By the way, could you send along a copy of the stress test script? >> > >> >> Paul, these scenarios are not scripted but end user tests with >> additional devices >> (WLAN, which is connected on the same controller) and executed 'on field' . > > OK, thanks Venkat. Do you still have one of these devices so the test can > be repeated? > >> One such log is here .. http://pastebin.com/nq3cfZnT > > Looks like this is an Android 2.6.35.7-derived kernel on a 4430 ES2.2 EMU. > Power management is enabled but MPU, L3INIT, and PER aren't entering any > deeper power states than retention idle, so no context save/restore or > off-mode worries here. > > The system looks like it's entered suspend at least once and resumed, > before the oops. Also the second CPU is starting up and shutting down > dynamically. Backtrace is copied below for the archives. > > Does the above summary match your understanding? Yes it does. > > ... > > Reviewing this backtrace and the one that Balaji sent, it looks to > me like this write in omap_hsmmc_prepare_data() is the proximate > cause of the abort: > > OMAP_HSMMC_WRITE(host->base, BLK, (req->data->blksz) > | (req->data->blocks << 16)); > > I'll bet this was first access to the MMC IP block after the MMC layer > re-enabled it. The abort is imprecise because the Linux OMAP4 kernel > marks MMIO registers as bufferable, so the ARM can continue executing > while a register write is making its way across the OMAP interconnect(s). > This guess also assumes that the ARM is executing instructions out of > order, which is a reasonable assumption on a Cortex-A9. This could be > confirmed by reading some HSMMC register right before the > OMAP_HSMMC_WRITE(); then the abort would turn precise and occur on the > read. Yes - The issue is not an issue with the set_data_timeout function but the _first_ access to MMC IP register blocks after enabling the mmc_host. (This backtrace signature is very common during MMC-PM hackathons ) But I have not seen any difference if the access is read or write.. Will check again.. > > Anyway, it looks like the HSMMC IP block wasn't yet ready to be accessed. > Probably, this is because either the HSMMC IP block hasn't yet left the > Idle or SleepTrans states, and the OMAP4 clock framework doesn't wait for > that; or the PRCM is getting confused because the correct clockdomain > enable sequence isn't being followed -- see for example the "Fix > module-mode enable sequence on OMAP4" patch series that have been posted > to the linux-omap mailing list. Probably one of those two issues is the > root cause. > > If you have a testing setup where you can reproduce this problem, I'd > suggest adding the read as described above. Otherwise, I don't think this > will be an issue for the runtime PM conversion: first, because the hwmod > code will wait for the HSMMC block to indicate that it has left idle > before continuing; and second, because we'll hopefully have a patch series > going in at the same time to make sure the clockdomain enable sequence is > correct. > As you might have guessed, the test setup is not accessible for me and it's not a simulated environment or scripted test. I'll try to check if some testcases can be written to simulate this. > > - Paul > > > <0> Process mmcqd (pid: 851, stack limit = 0xef9682f8) > <0> Stack: (0xef969db8 to 0xef96a000) > <0> 9da0: ef969ee4 efa30640 > <0> 9dc0: ef969e78 00000000 00000001 efa30400 ef969e2c ef969de0 c06ae2b8 c06ace10 > <0> 9de0: 00000000 efa305d8 ef969e04 efa30400 00000000 efa30578 ef969e44 ef969e08 > <0> 9e00: c054ea5c ef969e78 efa30400 ef969e34 00000001 ef837e4c 00000000 ef969ee4 > <0> 9e20: ef969e64 ef969e30 c06a54d8 c06adff4 00000000 00000000 00000000 00000000 > <0> 9e40: ef969e40 ef969e40 ed3d4680 ed3d4680 efa30c00 ef837e40 ef969f94 ef969e68 > <0> 9e60: c06abe80 c06a53cc 00000000 efa31458 ef0cfdb4 ef0cfdb4 ef969e8c ef969ee4 > <0> 9e80: ef969eb8 ef969e34 c06a55d0 00000019 00fd50a2 00000000 00000000 00000000 > <0> 9ea0: 00000000 000000b5 00000000 00000000 ef969ee4 ef969e78 0000000c 00000000 > <0> 9ec0: 00000000 00000000 00000000 00000000 0000049d 00000000 00000000 00000000 > <0> 9ee0: ef969e78 23c34600 00000fa0 00000200 00000400 00000000 00000100 00000000 > <0> 9f00: ef969eb8 ef969e78 0000003f ef238000 ef969f54 ef969f20 c0556c00 c0555fac > <0> 9f20: ef969f3c 00000001 c0425fa0 ef837e4c ef230000 ef837e54 ef837e4c ef230000 > <0> 9f40: ef837e54 ef230000 ef969f7c ef969f58 00000000 ed3d4680 ef969f7c ef969f68 > <0> 9f60: c054911c c054ee7c 01082e21 ef837e4c ef968000 ef837e54 ef230000 ef2301d8 > <0> 9f80: 00000000 ed3d4680 ef969fbc ef969f98 c06acab8 c06abccc ef985d68 ef969fc4 > <0> 9fa0: c06ac9c4 ef837e4c 00000000 00000000 ef969ff4 ef969fc0 c041fd20 c06ac9d0 > <0> 9fc0: 00000000 00000000 00000000 00000000 ef969fd0 ef969fd0 ef985d68 c041fc9c > <0> 9fe0: c040d67c 00000013 00000000 ef969ff8 c040d67c c041fca8 00000000 00000000 > <4> Backtrace: > <4> [<c06ace04>] (set_data_timeout+0x0/0xcc) from [<c06ae2b8>] (omap_hsmmc_request+0x2d0/0x5c8) > <4> r8:efa30400 r7:00000001 r6:00000000 r5:ef969e78 r4:efa30640 > <4> r3:ef969ee4 > <4> [<c06adfe8>] (omap_hsmmc_request+0x0/0x5c8) from [<c06a54d8>] (mmc_wait_for_req+0x118/0x130) > <4> [<c06a53c0>] (mmc_wait_for_req+0x0/0x130) from [<c06abe80>] (mmc_blk_issue_rq+0x1c0/0x500) > <4> r6:ef837e40 r5:efa30c00 r4:ed3d4680 > <4> [<c06abcc0>] (mmc_blk_issue_rq+0x0/0x500) from [<c06acab8>] (mmc_queue_thread+0xf4/0xf8) > <4> [<c06ac9c4>] (mmc_queue_thread+0x0/0xf8) from [<c041fd20>] (kthread+0x84/0x8c) > <4> [<c041fc9c>] (kthread+0x0/0x8c) from [<c040d67c>] (do_exit+0x0/0x604) > <4> r7:00000013 r6:c040d67c r5:c041fc9c r4:ef985d68 > <0> Code: 11a0c423 11c0c0b0 e1a0f00e e2512001 (01a0f00e) > <4> ---[ end trace d27fcce5bd5b71d6 ]--- > > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
