From: Kalle Valo <kvalo@codeaurora.org>
To: Brian Norris <briannorris@chromium.org>
Cc: Carl Huang <cjhuang@codeaurora.org>,
linux-wireless@vger.kernel.org, ath10k@lists.infradead.org,
Wen Gong <wgong@codeaurora.org>
Subject: Re: [PATCH] ath10k: pci: use mutex for diagnostic window CE polling
Date: Mon, 11 Feb 2019 16:32:30 +0000 (UTC) [thread overview]
Message-ID: <20190211163230.B4A4F60208@smtp.codeaurora.org> (raw)
In-Reply-To: <20190207014143.41529-1-briannorris@chromium.org>
Brian Norris <briannorris@chromium.org> wrote:
> The DIAG copy engine is only used via polling, but it holds a spinlock
> with softirqs disabled. Each iteration of our read/write loops can
> theoretically take 20ms (two 10ms timeout loops), and this loop can be
> run an unbounded number of times while holding the spinlock -- dependent
> on the request size given by the caller.
>
> As of commit 39501ea64116 ("ath10k: download firmware via diag Copy
> Engine for QCA6174 and QCA9377."), we transfer large chunks of firmware
> memory using this mechanism. With large enough firmware segments, this
> becomes an exceedingly long period for disabling soft IRQs. For example,
> with a 500KiB firmware segment, in testing QCA6174A, I see 200 loop
> iterations of about 50-100us each, which can total about 10-20ms.
>
> In reality, we don't really need to block softirqs for this duration.
> The DIAG CE is only used in polling mode, and we only need to hold
> ce_lock to make sure any CE bookkeeping is done without screwing up
> another CE. Otherwise, we only need to ensure exclusion between
> ath10k_pci_diag_{read,write}_mem() contexts.
>
> This patch moves to use fine-grained locking for the shared ce_lock,
> while adding a new mutex just to ensure mutual exclusion of diag
> read/write operations.
>
> Tested on QCA6174A, firmware version WLAN.RM.4.4.1-00132-QCARMSWPZ-1.
>
> Fixes: 39501ea64116 ("ath10k: download firmware via diag Copy Engine for QCA6174 and QCA9377.")
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Patch applied to ath-next branch of ath.git, thanks.
25733c4e67df ath10k: pci: use mutex for diagnostic window CE polling
--
https://patchwork.kernel.org/patch/10800343/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k
next prev parent reply other threads:[~2019-02-11 16:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 1:41 [PATCH] ath10k: pci: use mutex for diagnostic window CE polling Brian Norris
2019-02-11 16:32 ` Kalle Valo [this message]
2019-03-25 20:27 ` Brian Norris
2019-03-25 21:20 ` Michał Kazior
2019-03-25 22:14 ` Brian Norris
2019-03-26 20:35 ` Brian Norris
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190211163230.B4A4F60208@smtp.codeaurora.org \
--to=kvalo@codeaurora.org \
--cc=ath10k@lists.infradead.org \
--cc=briannorris@chromium.org \
--cc=cjhuang@codeaurora.org \
--cc=linux-wireless@vger.kernel.org \
--cc=wgong@codeaurora.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox