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SubjectRe: [PATCH v2 03/19] PM / devfreq: tegra: Don't ignore clk errors
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16.04.2019 4:52, Chanwoo Choi пишет:
> Hi,
>
> On 19. 4. 15. 오후 11:54, Dmitry Osipenko wrote:
>> The clk_set_min_rate() could fail and in this case clk_set_rate() sets
>> rate to 0, which may drop EMC rate to minimum and make machine very
>> difficult to use.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>> drivers/devfreq/tegra-devfreq.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
>> index 0c0909fba545..69581c9082d4 100644
>> --- a/drivers/devfreq/tegra-devfreq.c
>> +++ b/drivers/devfreq/tegra-devfreq.c
>> @@ -487,6 +487,7 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>> struct tegra_devfreq *tegra = dev_get_drvdata(dev);
>> struct dev_pm_opp *opp;
>> unsigned long rate;
>> + int err;
>>
>> opp = devfreq_recommended_opp(dev, freq, flags);
>> if (IS_ERR(opp)) {
>> @@ -496,8 +497,13 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>> rate = dev_pm_opp_get_freq(opp);
>> dev_pm_opp_put(opp);
>>
>> - clk_set_min_rate(tegra->emc_clock, rate);
>> - clk_set_rate(tegra->emc_clock, 0);
>> + err = clk_set_min_rate(tegra->emc_clock, rate);
>> + if (err)
>> + return err;
>> +
>> + err = clk_set_rate(tegra->emc_clock, 0);
>> + if (err)
>
> Why don't you restore the previous minimum clock for tegra->emc_clock
> when failed to execute 'clk_set_rate(tegra->emc_clock, 0);'?
>
> I think that if you control the restoring the previous minimum clock,
> it is more nice to handle the error handling.

I now see that devfreq has the previous_freq field and indeed it is possible to restore the min_rate value using it. Thanks for the suggestion.

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