| Message ID | d492617ed38eb7953401c3171bb3e08c48b7b431.1570976384.git.ps@pks.im (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ath10k: fix disabling of UART debugging | expand |
+ linux-wireless Patrick Steinhardt <ps@pks.im> writes: > Starting with v5.3.0, it was observed that throughput of an access point > with QCA988x-based wireless chip is severely degraded from at least > 10MB/s to roughly 200KB/s. A bisect of the issue points to commit > 4504f0e5b571 (ath10k: sdio: workaround firmware UART pin configuration > bug, 2019-04-19), which employs a workaround for a firmware bug in some > QCA6174 SDIO devices. > > If UART debugging is disabled via the "ath10k.uart_print" module > parameter, then the UART initialization code is skipped. With the new > workaround introduced in the mentioned commit, devices that need the > workaround will also re-set the UART pin of the device to avoid a > failing SDIO interrupt. But in fact, the change effectively removed the > early return for all devices that do not use the workaround, and as a > result UART debugging is now unconditionally turned on disregarding the > value of "ath10k.uart_print", causing the decrease in throughput. > > Fix the issue by re-introducing the early return for all devices again, > independent of the UART pin workaround. Tests show that throughput is > back to normal levels again with this fix. > > Fixes: 4504f0e5b571 ("ath10k: sdio: workaround firmware UART pin configuration bug") > Signed-off-by: Patrick Steinhardt <ps@pks.im> > --- > drivers/net/wireless/ath/ath10k/core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c > index dc45d16e8d21..8e4ca231634d 100644 > --- a/drivers/net/wireless/ath/ath10k/core.c > +++ b/drivers/net/wireless/ath/ath10k/core.c > @@ -2125,9 +2125,10 @@ static int ath10k_init_uart(struct ath10k *ar) > ath10k_warn(ar, "failed to set UART TX pin: %d", ret); > return ret; > } > + } > > + if (!uart_print) > return 0; > - } This was fixed in -next with a similar (but not identical) patch, but as there have been multiple reports of this issues I have now cherry picked it also for v5.4: https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers.git/commit/?id=d79749f7716d9dc32fa2d5075f6ec29aac63c76d
diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c index dc45d16e8d21..8e4ca231634d 100644 --- a/drivers/net/wireless/ath/ath10k/core.c +++ b/drivers/net/wireless/ath/ath10k/core.c @@ -2125,9 +2125,10 @@ static int ath10k_init_uart(struct ath10k *ar) ath10k_warn(ar, "failed to set UART TX pin: %d", ret); return ret; } + } + if (!uart_print) return 0; - } ret = ath10k_bmi_write32(ar, hi_dbg_uart_txpin, ar->hw_params.uart_pin); if (ret) {
Starting with v5.3.0, it was observed that throughput of an access point with QCA988x-based wireless chip is severely degraded from at least 10MB/s to roughly 200KB/s. A bisect of the issue points to commit 4504f0e5b571 (ath10k: sdio: workaround firmware UART pin configuration bug, 2019-04-19), which employs a workaround for a firmware bug in some QCA6174 SDIO devices. If UART debugging is disabled via the "ath10k.uart_print" module parameter, then the UART initialization code is skipped. With the new workaround introduced in the mentioned commit, devices that need the workaround will also re-set the UART pin of the device to avoid a failing SDIO interrupt. But in fact, the change effectively removed the early return for all devices that do not use the workaround, and as a result UART debugging is now unconditionally turned on disregarding the value of "ath10k.uart_print", causing the decrease in throughput. Fix the issue by re-introducing the early return for all devices again, independent of the UART pin workaround. Tests show that throughput is back to normal levels again with this fix. Fixes: 4504f0e5b571 ("ath10k: sdio: workaround firmware UART pin configuration bug") Signed-off-by: Patrick Steinhardt <ps@pks.im> --- drivers/net/wireless/ath/ath10k/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)