From: Stephen Boyd <swboyd@chromium.org>
To: Maulik Shah <mkshah@codeaurora.org>,
bjorn.andersson@linaro.org, evgreen@chromium.org,
mka@chromium.org
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
agross@kernel.org, dianders@chromium.org, rnayak@codeaurora.org,
ilina@codeaurora.org, lsrao@codeaurora.org,
Maulik Shah <mkshah@codeaurora.org>
Subject: Re: [PATCH v7 2/3] soc: qcom: rpmh: Update dirty flag only when data changes
Date: Wed, 26 Feb 2020 14:43:23 -0800 [thread overview]
Message-ID: <158275700389.177367.5843608826404724304@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <1582694833-9407-3-git-send-email-mkshah@codeaurora.org>
Quoting Maulik Shah (2020-02-25 21:27:12)
> Currently rpmh ctrlr dirty flag is set for all cases regardless
> of data is really changed or not. Add changes to update it when
> data is updated to newer values.
>
> Also move dirty flag updates to happen from within cache_lock.
>
> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
> Reviewed-by: Srinivas Rao L <lsrao@codeaurora.org>
Probably worth adding a Fixes tag here? Doesn't make sense to mark
something dirty when it isn't changed.
> ---
> drivers/soc/qcom/rpmh.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
> index eb0ded0..83ba4e0 100644
> --- a/drivers/soc/qcom/rpmh.c
> +++ b/drivers/soc/qcom/rpmh.c
> @@ -139,20 +139,27 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
> existing:
> switch (state) {
> case RPMH_ACTIVE_ONLY_STATE:
> - if (req->sleep_val != UINT_MAX)
> + if (req->sleep_val != UINT_MAX) {
> req->wake_val = cmd->data;
> + ctrlr->dirty = true;
> + }
> break;
> case RPMH_WAKE_ONLY_STATE:
> - req->wake_val = cmd->data;
> + if (req->wake_val != cmd->data) {
> + req->wake_val = cmd->data;
> + ctrlr->dirty = true;
> + }
> break;
> case RPMH_SLEEP_STATE:
> - req->sleep_val = cmd->data;
> + if (req->sleep_val != cmd->data) {
> + req->sleep_val = cmd->data;
> + ctrlr->dirty = true;
> + }
> break;
> default:
> break;
Please remove the default case. There are only three states in the enum. The
compiler will warn if a switch statement doesn't cover all cases and
we'll know to add something here if another enum value is added in the
future.
> }
>
> - ctrlr->dirty = true;
> unlock:
> spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
>
> @@ -323,6 +331,7 @@ static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
> list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
> kfree(req);
> INIT_LIST_HEAD(&ctrlr->batch_cache);
> + ctrlr->dirty = true;
> spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
> }
>
> @@ -456,6 +465,7 @@ static int send_single(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
> int rpmh_flush(struct rpmh_ctrlr *ctrlr)
> {
> struct cache_req *p;
> + unsigned long flags;
> int ret;
>
> if (!ctrlr->dirty) {
> @@ -488,7 +498,9 @@ int rpmh_flush(struct rpmh_ctrlr *ctrlr)
> return ret;
> }
>
> + spin_lock_irqsave(&ctrlr->cache_lock, flags);
> ctrlr->dirty = false;
> + spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
So we take the spinlock to update it here. But we don't hold the
spinlock to test for !dirty up above. Seems like either rpmh_flush() can
only be called sequentially, or the lock added here needs to be held
during the whole flush. Which way is it?
next prev parent reply other threads:[~2020-02-26 22:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 5:27 [PATCH v6 0/3] Invoke rpmh_flush for non OSI targets Maulik Shah
2020-02-26 5:27 ` [PATCH v7 1/3] arm64: dts: qcom: sc7180: Add cpuidle low power states Maulik Shah
2020-02-26 22:37 ` Stephen Boyd
2020-02-26 5:27 ` [PATCH v7 2/3] soc: qcom: rpmh: Update dirty flag only when data changes Maulik Shah
2020-02-26 22:43 ` Stephen Boyd [this message]
2020-02-27 5:32 ` Maulik Shah
2020-02-26 5:27 ` [PATCH v7 3/3] soc: qcom: rpmh: Invoke rpmh_flush for dirty caches Maulik Shah
2020-02-26 22:49 ` Stephen Boyd
2020-02-27 5:21 ` Maulik Shah
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=158275700389.177367.5843608826404724304@swboyd.mtv.corp.google.com \
--to=swboyd@chromium.org \
--cc=agross@kernel.org \
--cc=bjorn.andersson@linaro.org \
--cc=dianders@chromium.org \
--cc=evgreen@chromium.org \
--cc=ilina@codeaurora.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lsrao@codeaurora.org \
--cc=mka@chromium.org \
--cc=mkshah@codeaurora.org \
--cc=rnayak@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;
as well as URLs for NNTP newsgroup(s).