[v4,5/5] brcmfmac: sdio: Don't tune while the card is off
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Message ID 20190613234153.59309-6-dianders@chromium.org
State New
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Series
  • brcmfmac: sdio: Deal better w/ transmission errors related to idle
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Commit Message

Doug Anderson June 13, 2019, 11:41 p.m. UTC
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 a sleep command, so presumably that "good enough"
tuning is enough to wake us up, at least with a few retries.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

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(+)

Comments

Adrian Hunter June 17, 2019, 8:28 a.m. UTC | #1
On 14/06/19 2:41 AM, Douglas Anderson wrote:
> 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 a sleep command, so presumably that "good enough"
> tuning is enough to wake us up, at least with a few retries.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> 
> 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;
>
Arend Van Spriel June 17, 2019, 10:52 a.m. UTC | #2
On 6/14/2019 1:41 AM, Douglas Anderson wrote:
> 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 a sleep command, so presumably that "good enough"
> tuning is enough to wake us up, at least with a few retries.

The term "sleep command" is a bit confusing. There actually is a CMD14 
defined in the eSD spec, but that is not what we are using (unless we 
program the chip to do so) here. It is simply a specific register access 
using CMD52.

Apart from that....

Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

I think the stable version is mostly determined by change in MMC/SDIO so 
4.18 as mentioned Adrian seems most sensible. bcm4354 support was 
introduced in 3.14 and there were some earlier devices (4335) using same 
sleep mechanism.

Regards,
Arend

Patch
diff mbox series

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;