[PATCH v5 2/5] mmc: core: API to temporarily disable retuning for SDIO CRC errors

[PATCH v5 2/5] mmc: core: API to temporarily disable retuning for SDIO CRC errors

[Douglas Anderson]

Normally when the MMC core sees an "-EILSEQ" error returned by a host
controller then it will trigger a retuning of the card.  This is
generally a good idea.

However, if a command is expected to sometimes cause transfer errors
then these transfer errors shouldn't cause a re-tuning.  This
re-tuning will be a needless waste of time.  One example case where a
transfer is expected to cause errors is when transitioning between
idle (sometimes referred to as "sleep" in Broadcom code) and active
state on certain Broadcom WiFi SDIO cards.  Specifically if the card
was already transitioning between states when the command was sent it
could cause an error on the SDIO bus.

Let's add an API that the SDIO function drivers can call that will
temporarily disable the auto-tuning functionality.  Then we can add a
call to this in the Broadcom WiFi driver and any other driver that
might have similar needs.

NOTE: this makes the assumption that the card is already tuned well
enough that it's OK to disable the auto-retuning during one of these
error-prone situations.  Presumably the driver code performing the
error-prone transfer knows how to recover / retry from errors.  ...and
after we can get back to a state where transfers are no longer
error-prone then we can enable the auto-retuning again.  If we truly
find ourselves in a case where the card needs to be retuned sometimes
to handle one of these error-prone transfers then we can always try a
few transfers first without auto-retuning and then re-try with
auto-retuning if the first few fail.

Without this change on rk3288-veyron-minnie I periodically see this in
the logs of a machine just sitting there idle:
  dwmmc_rockchip ff0d0000.dwmmc: Successfully tuned phase to XYZ

Commit notes:
Patches #2 - #5 will go through Ulf's tree.
END

Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors")
Cc: stable@vger.kernel.org
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
---

Changes in v5:
- Add missing sdio_retune_crc_enable() in comments (Ulf).
- /s/reneable/re-enable (Ulf).
- Remove leftover prototypes: mmc_expect_errors_begin() / end() (Ulf).

Changes in v4:
- Moved to SDIO API only (Adrian, Ulf).
- Renamed to make it less generic, now retune_crc_disable (Ulf).
- Function header makes it clear host must be claimed (Ulf).
- No more WARN_ON (Ulf).

Changes in v3:
- Took out the spinlock since I believe this is all in one context.

Changes in v2:
- Updated commit message to clarify based on discussion of v1.

 drivers/mmc/core/core.c       |  5 +++--
 drivers/mmc/core/sdio_io.c    | 37 +++++++++++++++++++++++++++++++++++
 include/linux/mmc/host.h      |  1 +
 include/linux/mmc/sdio_func.h |  3 +++
 4 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6db36dc870b5..9020cb2490f7 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -144,8 +144,9 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
 	int err = cmd->error;
 
 	/* Flag re-tuning needed on CRC errors */
-	if ((cmd->opcode != MMC_SEND_TUNING_BLOCK &&
-	    cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200) &&
+	if (cmd->opcode != MMC_SEND_TUNING_BLOCK &&
+	    cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200 &&
+	    !host->retune_crc_disable &&
 	    (err == -EILSEQ || (mrq->sbc && mrq->sbc->error == -EILSEQ) ||
 	    (mrq->data && mrq->data->error == -EILSEQ) ||
 	    (mrq->stop && mrq->stop->error == -EILSEQ)))
diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index f79f0b0caab8..0acb1a29c968 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -734,3 +734,40 @@ int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(sdio_set_host_pm_flags);
+
+/**
+ *	sdio_retune_crc_disable - temporarily disable retuning on CRC errors
+ *	@func: SDIO function attached to host
+ *
+ *	If the SDIO card is known to be in a state where it might produce
+ *	CRC errors on the bus in response to commands (like if we know it is
+ *	transitioning between power states), an SDIO function driver can
+ *	call this function to temporarily disable the SD/MMC core behavior of
+ *	triggering an automatic retuning.
+ *
+ *	This function should be called while the host is claimed and the host
+ *	should remain claimed until sdio_retune_crc_enable() is called.
+ *	Specifically, the expected sequence of calls is:
+ *	- sdio_claim_host()
+ *	- sdio_retune_crc_disable()
+ *	- some number of calls like sdio_writeb() and sdio_readb()
+ *	- sdio_retune_crc_enable()
+ *	- sdio_release_host()
+ */
+void sdio_retune_crc_disable(struct sdio_func *func)
+{
+	func->card->host->retune_crc_disable = true;
+}
+EXPORT_SYMBOL_GPL(sdio_retune_crc_disable);
+
+/**
+ *	sdio_retune_crc_enable - re-enable retuning on CRC errors
+ *	@func: SDIO function attached to host
+ *
+ *	This is the compement to sdio_retune_crc_disable().
+ */
+void sdio_retune_crc_enable(struct sdio_func *func)
+{
+	func->card->host->retune_crc_disable = false;
+}
+EXPORT_SYMBOL_GPL(sdio_retune_crc_enable);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 43d0f0c496f6..ecb7972e2423 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -398,6 +398,7 @@ struct mmc_host {
 	unsigned int		retune_now:1;	/* do re-tuning at next req */
 	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
 	unsigned int		use_blk_mq:1;	/* use blk-mq */
+	unsigned int		retune_crc_disable:1; /* don't trigger retune upon crc */
 
 	int			rescan_disable;	/* disable card detection */
 	int			rescan_entered;	/* used with nonremovable devices */
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index e9dfdd501cd1..4820e6d09dac 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -167,4 +167,7 @@ extern void sdio_f0_writeb(struct sdio_func *func, unsigned char b,
 extern mmc_pm_flag_t sdio_get_host_pm_caps(struct sdio_func *func);
 extern int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags);
 
+extern void sdio_retune_crc_disable(struct sdio_func *func);
+extern void sdio_retune_crc_enable(struct sdio_func *func);
+
 #endif /* LINUX_MMC_SDIO_FUNC_H */
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH v5 3/5] brcmfmac: sdio: Disable auto-tuning around commands expected to fail

[Douglas Anderson]

There are certain cases, notably when transitioning between sleep and
active state, when Broadcom SDIO WiFi cards will produce errors on the
SDIO bus.  This is evident from the source code where you can see that
we try commands in a loop until we either get success or we've tried
too many times.  The comment in the code reinforces this by saying
"just one write attempt may fail"

Unfortunately these failures sometimes end up causing an "-EILSEQ"
back to the core which triggers a retuning of the SDIO card and that
blocks all traffic to the card until it's done.

Let's disable retuning around the commands we expect might fail.

Commit notes:
Patches #2 - #5 will go through Ulf's tree.

This patch is still lacking Kalle Valo's Ack, which should probably be
received before landing in Ulf's tree.
END

Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors")
Cc: stable@vger.kernel.org
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
---

Changes in v5: None
Changes in v4:
- Adjust to API rename (Adrian, Ulf).

Changes in v3:
- Expect errors for all of brcmf_sdio_kso_control() (Adrian).

Changes in v2: None

 drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index 4a750838d8cd..ee76593259a7 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -667,6 +667,8 @@ brcmf_sdio_kso_control(struct brcmf_sdio *bus, bool on)
 
 	brcmf_dbg(TRACE, "Enter: on=%d\n", on);
 
+	sdio_retune_crc_disable(bus->sdiodev->func1);
+
 	wr_val = (on << SBSDIO_FUNC1_SLEEPCSR_KSO_SHIFT);
 	/* 1st KSO write goes to AOS wake up core if device is asleep  */
 	brcmf_sdiod_writeb(bus->sdiodev, SBSDIO_FUNC1_SLEEPCSR, wr_val, &err);
@@ -727,6 +729,8 @@ brcmf_sdio_kso_control(struct brcmf_sdio *bus, bool on)
 	if (try_cnt > MAX_KSO_ATTEMPTS)
 		brcmf_err("max tries: rd_val=0x%x err=%d\n", rd_val, err);
 
+	sdio_retune_crc_enable(bus->sdiodev->func1);
+
 	return err;
 }
 
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH v5 4/5] mmc: core: Add sdio_retune_hold_now() and sdio_retune_release()

[Douglas Anderson]

We want SDIO drivers to be able to temporarily stop retuning when the
driver knows that the SDIO card is not in a state where retuning will
work (maybe because the card is asleep).  We'll move the relevant
functions to a place where drivers can call them.

Cc: stable@vger.kernel.org
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
---
Patches #2 - #5 will go through Ulf's tree.

I've CCed stable@ here without a version tag.  As per Adrian Hunter
this patch applies cleanly to 4.18+ so that would be an easy first
target.  However, if someone were so inclined they could provide
further backports.  As per Adrian [1] the root problem has existed for
~4 years.

[1] https://lkml.kernel.org/r/4f39e152-04ba-a64e-985a-df93e6d15ff8@intel.com

Changes in v5: None
Changes in v4:
- Moved retune hold/release to SDIO API (Adrian).

Changes in v3:
- ("mmc: core: Export mmc_retune_hold_now() mmc_retune_release()") new for v3.

Changes in v2: None

 drivers/mmc/core/sdio_io.c    | 40 +++++++++++++++++++++++++++++++++++
 include/linux/mmc/sdio_func.h |  3 +++
 2 files changed, 43 insertions(+)

diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index 0acb1a29c968..2ba00acf64e6 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -15,6 +15,7 @@
 #include "sdio_ops.h"
 #include "core.h"
 #include "card.h"
+#include "host.h"
 
 /**
  *	sdio_claim_host - exclusively claim a bus for a certain SDIO function
@@ -771,3 +772,42 @@ void sdio_retune_crc_enable(struct sdio_func *func)
 	func->card->host->retune_crc_disable = false;
 }
 EXPORT_SYMBOL_GPL(sdio_retune_crc_enable);
+
+/**
+ *	sdio_retune_hold_now - start deferring retuning requests till release
+ *	@func: SDIO function attached to host
+ *
+ *	This function can be called if it's currently a bad time to do
+ *	a retune of the SDIO card.  Retune requests made during this time
+ *	will be held and we'll actually do the retune sometime after the
+ *	release.
+ *
+ *	This function could be useful if an SDIO card is in a power state
+ *	where it can respond to a small subset of commands that doesn't
+ *	include the retuning command.  Care should be taken when using
+ *	this function since (presumably) the retuning request we might be
+ *	deferring was made for a good reason.
+ *
+ *	This function should be called while the host is claimed.
+ */
+void sdio_retune_hold_now(struct sdio_func *func)
+{
+	mmc_retune_hold_now(func->card->host);
+}
+EXPORT_SYMBOL_GPL(sdio_retune_hold_now);
+
+/**
+ *	sdio_retune_release - signal that it's OK to retune now
+ *	@func: SDIO function attached to host
+ *
+ *	This is the complement to sdio_retune_hold_now().  Calling this
+ *	function won't make a retune happen right away but will allow
+ *	them to be scheduled normally.
+ *
+ *	This function should be called while the host is claimed.
+ */
+void sdio_retune_release(struct sdio_func *func)
+{
+	mmc_retune_release(func->card->host);
+}
+EXPORT_SYMBOL_GPL(sdio_retune_release);
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index 4820e6d09dac..5a177f7a83c3 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -170,4 +170,7 @@ extern int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags);
 extern void sdio_retune_crc_disable(struct sdio_func *func);
 extern void sdio_retune_crc_enable(struct sdio_func *func);
 
+extern void sdio_retune_hold_now(struct sdio_func *func);
+extern void sdio_retune_release(struct sdio_func *func);
+
 #endif /* LINUX_MMC_SDIO_FUNC_H */
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH v5 5/5] brcmfmac: sdio: Don't tune while the card is off

[Douglas Anderson]

When Broadcom SDIO cards are idled they go to sleep and a whole
separate subsystem takes over their SDIO communication.  This is the
Always-On-Subsystem (AOS) and it can't handle tuning requests.

Specifically, as tested on rk3288-veyron-minnie (which reports having
BCM4354/1 in dmesg), if I force a retune in brcmf_sdio_kso_control()
when "on = 1" (aka we're transition from sleep to wake) by whacking:
  bus->sdiodev->func1->card->host->need_retune = 1
...then I can often see tuning fail.  In this case dw_mmc reports "All
phases bad!").  Note that I don't get 100% failure, presumably because
sometimes the card itself has already transitioned away from the AOS
itself by the time we try to wake it up.  If I force retuning when "on
= 0" (AKA force retuning right before sending the command to go to
sleep) then retuning is always OK.

NOTE: we need _both_ this patch and the patch to avoid triggering
tuning due to CRC errors in the sleep/wake transition, AKA ("brcmfmac:
sdio: Disable auto-tuning around commands expected to fail").  Though
both patches handle issues with Broadcom's AOS, the problems are
distinct:
1. We want to defer (but not ignore) asynchronous (like
   timer-requested) tuning requests till the card is awake.  However,
   we want to ignore CRC errors during the transition, we don't want
   to queue deferred tuning request.
2. You could imagine that the AOS could implement retuning but we
   could still get errors while transitioning in and out of the AOS.
   Similarly you could imagine a seamless transition into and out of
   the AOS (with no CRC errors) even if the AOS couldn't handle
   tuning.

ALSO NOTE: presumably there is never a desperate need to retune in
order to wake up the card, since doing so is impossible.  Luckily the
only way the card can get into sleep state is if we had a good enough
tuning to send it the command to put it into sleep, so presumably that
"good enough" tuning is enough to wake us up, at least with a few
retries.

Cc: stable@vger.kernel.org
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
---
Patches #2 - #5 will go through Ulf's tree.

This patch is still lacking Kalle Valo's Ack, which should probably be
received before landing in Ulf's tree.

I've CCed stable@ here without a version tag.  As per Adrian Hunter
this patch applies cleanly to 4.18+ so that would be an easy first
target.  However, if someone were so inclined they could provide
further backports.  As per Adrian [1] the root problem has existed for
~4 years.

[1] https://lkml.kernel.org/r/4f39e152-04ba-a64e-985a-df93e6d15ff8@intel.com

Changes in v5:
- Rewording of "sleep command" in commit message (Arend).

Changes in v4:
- Adjust to API rename (Adrian).

Changes in v3:
- ("brcmfmac: sdio: Don't tune while the card is off") new for v3.

Changes in v2: None

 drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index ee76593259a7..629140b6d7e2 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -669,6 +669,10 @@ brcmf_sdio_kso_control(struct brcmf_sdio *bus, bool on)
 
 	sdio_retune_crc_disable(bus->sdiodev->func1);
 
+	/* Cannot re-tune if device is asleep; defer till we're awake */
+	if (on)
+		sdio_retune_hold_now(bus->sdiodev->func1);
+
 	wr_val = (on << SBSDIO_FUNC1_SLEEPCSR_KSO_SHIFT);
 	/* 1st KSO write goes to AOS wake up core if device is asleep  */
 	brcmf_sdiod_writeb(bus->sdiodev, SBSDIO_FUNC1_SLEEPCSR, wr_val, &err);
@@ -729,6 +733,9 @@ brcmf_sdio_kso_control(struct brcmf_sdio *bus, bool on)
 	if (try_cnt > MAX_KSO_ATTEMPTS)
 		brcmf_err("max tries: rd_val=0x%x err=%d\n", rd_val, err);
 
+	if (on)
+		sdio_retune_release(bus->sdiodev->func1);
+
 	sdio_retune_crc_enable(bus->sdiodev->func1);
 
 	return err;
-- 
2.22.0.410.gd8fdbe21b5-goog