[PATCH] brcmfmac: reserve tx credit only when txctl is ready to send

[PATCH] brcmfmac: reserve tx credit only when txctl is ready to send

[Wright Feng]

The 4329 throughput drops from 40.2 Mbits/sec to 190 Kbits/sec in 2G
11n mode because the commit b41c232d33666 ("brcmfmac: reserve 2 credits
for host tx control path"). To fix the issue, host driver only reserves
tx control credit when there is a txctl frame is pending to send. And
we also check available credit by using "not equal to 0" instead of
"greater than 0" because tx_max and tx_seq are circled positive numbers.

Reported-by: Dmitry Osipenko <digetx@gmail.com>
Fixes: b41c232d33666 ("brcmfmac: reserve 2 credits for host tx control
path")
Signed-off-by: Wright Feng <wright.feng@cypress.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
---
 .../net/wireless/broadcom/brcm80211/brcmfmac/sdio.c  | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index e8712ad3ac45..3c07d1bbe1c6 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -664,9 +664,15 @@ static void pkt_align(struct sk_buff *p, int len, int align)
 /* To check if there's window offered */
 static bool data_ok(struct brcmf_sdio *bus)
 {
-	/* Reserve TXCTL_CREDITS credits for txctl */
-	return (bus->tx_max - bus->tx_seq) > TXCTL_CREDITS &&
-	       ((bus->tx_max - bus->tx_seq) & 0x80) == 0;
+	u8 tx_rsv = 0;
+
+	/* Reserve TXCTL_CREDITS credits for txctl when it is ready to send */
+	if (bus->ctrl_frame_stat)
+		tx_rsv = TXCTL_CREDITS;
+
+	return (bus->tx_max - bus->tx_seq - tx_rsv) != 0 &&
+	       ((bus->tx_max - bus->tx_seq - tx_rsv) & 0x80) == 0;
+
 }
 
 /* To check if there's window offered */
-- 
2.25.0

Re: [PATCH] brcmfmac: reserve tx credit only when txctl is ready to send

[Kalle Valo]

Wright Feng <wright.feng@cypress.com> writes:

> The 4329 throughput drops from 40.2 Mbits/sec to 190 Kbits/sec in 2G
> 11n mode because the commit b41c232d33666 ("brcmfmac: reserve 2 credits
> for host tx control path"). To fix the issue, host driver only reserves
> tx control credit when there is a txctl frame is pending to send. And
> we also check available credit by using "not equal to 0" instead of
> "greater than 0" because tx_max and tx_seq are circled positive numbers.
>
> Reported-by: Dmitry Osipenko <digetx@gmail.com>
> Fixes: b41c232d33666 ("brcmfmac: reserve 2 credits for host tx control
> path")

Fixes tag should be in one line, but I can fix it.

> Signed-off-by: Wright Feng <wright.feng@cypress.com>
> Tested-by: Dmitry Osipenko <digetx@gmail.com>

And I'll queue this to v5.9.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] brcmfmac: reserve tx credit only when txctl is ready to send

[Kalle Valo]

Wright Feng <wright.feng@cypress.com> wrote:

> The 4329 throughput drops from 40.2 Mbits/sec to 190 Kbits/sec in 2G
> 11n mode because the commit b41c232d33666 ("brcmfmac: reserve 2 credits
> for host tx control path"). To fix the issue, host driver only reserves
> tx control credit when there is a txctl frame is pending to send. And
> we also check available credit by using "not equal to 0" instead of
> "greater than 0" because tx_max and tx_seq are circled positive numbers.
> 
> Reported-by: Dmitry Osipenko <digetx@gmail.com>
> Fixes: b41c232d33666 ("brcmfmac: reserve 2 credits for host tx control path")
> Signed-off-by: Wright Feng <wright.feng@cypress.com>
> Tested-by: Dmitry Osipenko <digetx@gmail.com>

Patch applied to wireless-drivers.git, thanks.

9a2a0862d973 brcmfmac: reserve tx credit only when txctl is ready to send

-- 
https://patchwork.kernel.org/patch/11711809/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches