Hi Alim,
On Mon, February 03, 2014, Alim Akhtar wrote:
> Hi Ulf
>
> On Thu, Dec 19, 2013 at 12:04 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> > There are no reason to why the use of a non-volatile internal eMMC
> > cache should be controlled by a host cap. Instead let's just enable it
> > if the eMMC card supports it.
> >
> > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> > Acked-by: Seungwon Jeon <tgih.jun@xxxxxxxxxxx>
> > ---
> > drivers/mmc/core/core.c | 4 ----
> > drivers/mmc/core/mmc.c | 3 +--
> > include/linux/mmc/host.h | 1 -
> > 3 files changed, 1 insertion(+), 7 deletions(-)
> >
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index df591a9..1228a59 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -2582,12 +2582,8 @@ EXPORT_SYMBOL(mmc_power_restore_host);
> > */
> > int mmc_flush_cache(struct mmc_card *card)
> > {
> > - struct mmc_host *host = card->host;
> > int err = 0;
> >
> > - if (!(host->caps2 & MMC_CAP2_CACHE_CTRL))
> > - return err;
> > -
>
> I have back port this patch to a 3.8 based kernel and was testing
> cache_ctrl feature of emmc device.
> It gives below kernel panic with a suspend/resume cycle.
>
> ========
>
> 26.084474] Unable to handle kernel NULL pointer dereference at virtual
> address 000001bc
> [ 26.092203] pgd = eabb4000
> [ 26.100593] [000001bc] *pgd=00000000
> [ 26.104157] Internal error: Oops: 5 [#1] SMP ARM
> [ 26.138663] CPU: 0 Tainted: G C (3.8.11 #164)
> [ 26.144221] PC is at mmc_flush_cache+0x18/0xd4
> [ 26.148640] LR is at mmc_suspend_host+0x34/0x188
> [ 26.153238] pc : [<c03b2bd4>] lr : [<c03b3e54>] psr: 60000013
> [ 26.153238] sp : edf73d60 ip : edf73d88 fp : edf73d84
> [ 26.164687] r10: 00000002 r9 : c07d8b2c r8 : c07a6bc8
> [ 26.169892] r7 : ef2d5244 r6 : ede09818 r5 : ede09818 r4 :
> edddb400
> [ 26.176399] r3 : 271ae517 r2 : 271ae517 r1 : 60000013 r0 :
> 00000000
> [ 26.182906] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM
> Segment user
> [ 26.190019] Control: 10c5387d Table: 4abb406a DAC: 00000015
> [ 26.195744] Process cat (pid: 7087, stack limit = 0xedf72240)
> [ 26.377050] Backtrace:
> [ 26.379401] [<c03b2bd4>] (mmc_flush_cache+0x18/0xd4) from
> [<c03b3e54>] (mmc_suspend_host+0x34/0x188)
> [ 26.388506] [<c03b3e54>] (mmc_suspend_host+0x34/0x188) from
> [<c03c7e24>] (dw_mci_suspend+0x40/0x88)
> [ 26.397528] [<c03c7e24>] (dw_mci_suspend+0x40/0x88) from
> [<c03ca278>] (dw_mci_exynos_suspend+0x1c/0x20)
> [ 26.406898] [<c03ca278>] (dw_mci_exynos_suspend+0x1c/0x20) from
> [<c02d0a04>] (platform_pm_suspend+0x3c/0x64)
> [ 26.416701] [<c02d0a04>] (platform_pm_suspend+0x3c/0x64) from
> [<c02d594c>] (dpm_run_callback.isra.5+0x24/0x4c)
> [ 26.426677] [<c02d594c>] (dpm_run_callback.isra.5+0x24/0x4c) from
> [<c02d6564>] (__device_suspend+0x188/0x214)
> [ 26.436565] [<c02d6564>] (__device_suspend+0x188/0x214) from
> [<c02d6e44>] (dpm_suspend+0xbc/0x218)
> [ 26.445501] [<c02d6e44>] (dpm_suspend+0xbc/0x218) from [<c02d7200>]
> (dpm_suspend_start+0x6c/0x74)
> [ 26.454352] [<c02d7200>] (dpm_suspend_start+0x6c/0x74) from
> [<c006c944>] (suspend_devices_and_enter+0x8c/0x294)
> [ 26.464414] [<c006c944>] (suspend_devices_and_enter+0x8c/0x294) from
> [<c006cbfc>] (pm_suspend+0xb0/0x19c)
> [ 26.473955] [<c006cbfc>] (pm_suspend+0xb0/0x19c) from [<c006bd68>]
> (state_store+0xbc/0xd0)
> [ 26.482197] [<c006bd68>] (state_store+0xbc/0xd0) from [<c020ea20>]
> (kobj_attr_store+0x1c/0x28)
> [ 26.490787] [<c020ea20>] (kobj_attr_store+0x1c/0x28) from
> [<c015cfd0>] (sysfs_write_file+0x114/0x158)
> [ 26.499980] [<c015cfd0>] (sysfs_write_file+0x114/0x158) from
> [<c00fff08>] (vfs_write+0xbc/0x14c)
> [ 26.508741] [<c00fff08>] (vfs_write+0xbc/0x14c) from [<c0100098>]
> (sys_write+0x5c/0xa4)
> [ 26.516723] [<c0100098>] (sys_write+0x5c/0xa4) from [<c000e2c0>]
> (ret_fast_syscall+0x0/0x30)
> [ 26.525137] Code: e24cb004 e24dd00c e92d4000 e8bd4000 (e59011bc)
> [ 26.531276] ---[ end trace 04c2942721bcd221 ]---
> [ 26.537224] Kernel panic - not syncing: Fatal exception
>
> ========
> Looks like mmc_flush_cache() is called for even SD cards,
> and probably since SD cards does not have ext_csd register, and it is
> trying to access the same below, its give kernel panic.
> As my kernel is still 3.8, so I am not sure if I missed any other
> patch which is/are needed and already taking care of such crashes.
> By adding a check for card->type does make this crash goes away.
When you test, sd card slot is empty?
If right, 'card' can be NULL in kernel panic?
The reason mmc_flush_cache() is called for even SD cards that mmc_suspend_host()
is calling mmc_flush_cache().
There has been some changes related to cache feature before Ulf's patch.
mmc_cache_ctrl() has been moved to 'mmc.c' from 'core.c' and now Ulf replaces it with mmc_flush_cache().
I guess mmc_flush_cache() should not be called in mmc_suspend_host().
That means it's not applicable to your 3.8 kernel.
Thanks,
Seungwon Jeon
>
> + if (mmc_card_mmc(card) != MMC_TYPE_MMC)
> + return err;
>
> Do you know if this is the right thing to do?
>
> > if (mmc_card_mmc(card) &&
> > (card->ext_csd.cache_size > 0) &&
> > (card->ext_csd.cache_ctrl & 1)) {
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index ef1cc73..7ab3e9c 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -1287,8 +1287,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> > * If cache size is higher than 0, this indicates
> > * the existence of cache and it can be turned on.
> > */
> > - if ((host->caps2 & MMC_CAP2_CACHE_CTRL) &&
> > - card->ext_csd.cache_size > 0) {
> > + if (card->ext_csd.cache_size > 0) {
> > err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > EXT_CSD_CACHE_CTRL, 1,
> > card->ext_csd.generic_cmd6_time);
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index f539bc7..8383e3f 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -264,7 +264,6 @@ struct mmc_host {
> > u32 caps2; /* More host capabilities */
> >
> > #define MMC_CAP2_BOOTPART_NOACC (1 << 0) /* Boot partition no access */
> > -#define MMC_CAP2_CACHE_CTRL (1 << 1) /* Allow cache control */
> > #define MMC_CAP2_FULL_PWR_CYCLE (1 << 2) /* Can do full power cycle */
> > #define MMC_CAP2_NO_MULTI_READ (1 << 3) /* Multiblock reads don't work */
> > #define MMC_CAP2_NO_SLEEP_CMD (1 << 4) /* Don't allow sleep command */
> > --
> > 1.7.9.5
> >
> > --
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>
> --
> Regards,
> Alim
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