From: Lukasz Luba <lukasz.luba@arm.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Krzysztof Kozlowski <krzk@kernel.org>,
linux-samsung-soc@vger.kernel.org,
Chanwoo Choi <cw00.choi@samsung.com>
Subject: Re: [PATCH] memory: samsung: exynos5422-dmc: propagate error from exynos5_counters_get()
Date: Tue, 4 Aug 2020 10:11:03 +0100 [thread overview]
Message-ID: <24675559-b807-5b80-1318-805c1530ffb3@arm.com> (raw)
In-Reply-To: <20200804061210.5415-1-m.szyprowski@samsung.com>
Hi Marek,
On 8/4/20 7:12 AM, Marek Szyprowski wrote:
> exynos5_counters_get() might fail with -EPROBE_DEFER if the driver for
> devfreq event counter is not yet probed. Propagate that error value to
> the caller to ensure that the exynos5422-dmc driver will be probed again
> when devfreq event contuner is available.
>
> This fixes boot hang if both exynos5422-dmc and exynos-ppmu drivers are
> compiled as modules.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> drivers/memory/samsung/exynos5422-dmc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
> index b9c7956e5031..639811a3eecb 100644
> --- a/drivers/memory/samsung/exynos5422-dmc.c
> +++ b/drivers/memory/samsung/exynos5422-dmc.c
> @@ -914,7 +914,7 @@ static int exynos5_dmc_get_status(struct device *dev,
> } else {
> ret = exynos5_counters_get(dmc, &load, &total);
> if (ret < 0)
> - return -EINVAL;
> + return ret;
>
> /* To protect from overflow, divide by 1024 */
> stat->busy_time = load >> 10;
>
Thank you for the patch, LGTM.
Some questions are still there, though. The function
exynos5_performance_counters_init() should capture that the counters
couldn't be enabled or set. So the functions:
exynos5_counters_enable_edev() and exynos5_counters_set_event()
must pass gently because devfreq device is registered.
Then devfreq checks device status, and reaches the state when
counters 'get' function returns that they are not ready...
If that is a kind of 2-stage initialization, maybe we should add
another 'check' in the exynos5_performance_counters_init() and call
the devfreq_event_get_event() to make sure that we are ready to go,
otherwise return ret from that function (which is probably EPROBE_DEFER)
and not register the devfreq device.
Marek do want to submit such patch or I should bake it and submit on top
of this patch?
Could you tell me how I can reproduce this? Do you simply load one
module after another (exynos-ppmu than exynos5422-dmc) or in parallel?
Regards,
Lukasz
next prev parent reply other threads:[~2020-08-04 9:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200804061225eucas1p283c1e0dc404bc420a2184480fdfd2b0d@eucas1p2.samsung.com>
2020-08-04 6:12 ` [PATCH] memory: samsung: exynos5422-dmc: propagate error from exynos5_counters_get() Marek Szyprowski
2020-08-04 6:42 ` Krzysztof Kozlowski
2020-08-04 9:11 ` Lukasz Luba [this message]
2020-08-04 12:19 ` Marek Szyprowski
2020-08-04 12:38 ` Lukasz Luba
2020-08-17 12:07 ` Krzysztof Kozlowski
2020-08-17 12:27 ` Lukasz Luba
2020-08-24 7:44 ` Marek Szyprowski
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