Re: [PATCH v2 34/48] gpu: host1x: Support power management

[Dmitry Osipenko <digetx@gmail.com>]

17.12.2020 21:21, Mikko Perttunen пишет:
> On 12/17/20 8:06 PM, Dmitry Osipenko wrote:
>> Add suspend/resume and generic power domain support to the Host1x driver.
>> This is required for enabling system-wide DVFS and supporting dynamic
>> power management using a generic power domain.
>>
>> Tested-by: Peter Geis <pgwipeout@gmail.com>
>> Tested-by: Nicolas Chauvet <kwizart@gmail.com>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>   drivers/gpu/host1x/dev.c | 102 ++++++++++++++++++++++++++++++++++-----
>>   1 file changed, 91 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
>> index d0ebb70e2fdd..c1525cffe7b1 100644
>> --- a/drivers/gpu/host1x/dev.c
>> +++ b/drivers/gpu/host1x/dev.c
>> @@ -12,6 +12,7 @@
>>   #include <linux/module.h>
>>   #include <linux/of_device.h>
>>   #include <linux/of.h>
>> +#include <linux/pm_runtime.h>
>>   #include <linux/slab.h>
>>     #define CREATE_TRACE_POINTS
>> @@ -417,7 +418,7 @@ static int host1x_probe(struct platform_device *pdev)
>>           return err;
>>       }
>>   -    host->rst = devm_reset_control_get(&pdev->dev, "host1x");
>> +    host->rst = devm_reset_control_get_exclusive_released(&pdev->dev,
>> "host1x");
>>       if (IS_ERR(host->rst)) {
>>           err = PTR_ERR(host->rst);
>>           dev_err(&pdev->dev, "failed to get reset: %d\n", err);
>> @@ -437,16 +438,15 @@ static int host1x_probe(struct platform_device
>> *pdev)
>>           goto iommu_exit;
>>       }
>>   -    err = clk_prepare_enable(host->clk);
>> -    if (err < 0) {
>> -        dev_err(&pdev->dev, "failed to enable clock\n");
>> -        goto free_channels;
>> -    }
>> +    pm_runtime_enable(&pdev->dev);
>> +    err = pm_runtime_get_sync(&pdev->dev);
>> +    if (err < 0)
>> +        goto rpm_disable;
>>         err = reset_control_deassert(host->rst);
>>       if (err < 0) {
>>           dev_err(&pdev->dev, "failed to deassert reset: %d\n", err);
>> -        goto unprepare_disable;
>> +        goto rpm_disable;
>>       }
>>         err = host1x_syncpt_init(host);
>> @@ -485,9 +485,10 @@ static int host1x_probe(struct platform_device
>> *pdev)
>>       host1x_syncpt_deinit(host);
>>   reset_assert:
>>       reset_control_assert(host->rst);
>> -unprepare_disable:
>> -    clk_disable_unprepare(host->clk);
>> -free_channels:
>> +rpm_disable:
>> +    pm_runtime_put(&pdev->dev);
>> +    pm_runtime_disable(&pdev->dev);
>> +
>>       host1x_channel_list_free(&host->channel_list);
>>   iommu_exit:
>>       host1x_iommu_exit(host);
>> @@ -504,16 +505,95 @@ static int host1x_remove(struct platform_device
>> *pdev)
>>       host1x_intr_deinit(host);
>>       host1x_syncpt_deinit(host);
>>       reset_control_assert(host->rst);
>> -    clk_disable_unprepare(host->clk);
>> +    pm_runtime_put(&pdev->dev);
>> +    pm_runtime_disable(&pdev->dev);
>>       host1x_iommu_exit(host);
>>         return 0;
>>   }
>>   +static int __maybe_unused host1x_runtime_suspend(struct device *dev)
>> +{
>> +    struct host1x *host = dev_get_drvdata(dev);
>> +
>> +    clk_disable_unprepare(host->clk);
>> +    reset_control_release(host->rst);
>> +
>> +    return 0;
>> +}
>> +
>> +static int __maybe_unused host1x_runtime_resume(struct device *dev)
>> +{
>> +    struct host1x *host = dev_get_drvdata(dev);
>> +    int err;
>> +
>> +    err = reset_control_acquire(host->rst);
>> +    if (err) {
>> +        dev_err(dev, "failed to acquire reset: %d\n", err);
>> +        return err;
>> +    }
>> +
>> +    err = clk_prepare_enable(host->clk);
>> +    if (err) {
>> +        dev_err(dev, "failed to enable clock: %d\n", err);
>> +        goto release_reset;
>> +    }
>> +
>> +    return 0;
>> +
>> +release_reset:
>> +    reset_control_release(host->rst);
>> +
>> +    return err;
>> +}
>> +
>> +static __maybe_unused int host1x_suspend(struct device *dev)
>> +{
>> +    struct host1x *host = dev_get_drvdata(dev);
>> +    int err;
>> +
>> +    host1x_syncpt_save(host);
>> +
>> +    err = pm_runtime_force_suspend(dev);
>> +    if (err < 0)
>> +        return err;
>> +
>> +    return 0;
>> +}
>> +
>> +static __maybe_unused int host1x_resume(struct device *dev)
>> +{
>> +    struct host1x *host = dev_get_drvdata(dev);
>> +    struct host1x_channel *channel;
>> +    unsigned int index;
>> +    int err;
>> +
>> +    err = pm_runtime_force_resume(dev);
>> +    if (err < 0)
>> +        return err;
>> +
>> +    host1x_syncpt_restore(host);
> 
> We also need to execute 'host1x_setup_sid_table' upon resume.

Indeed, thanks. I'll correct it in the next revision.

Perhaps the actual save/restore needs to be moved to the runtime
callbacks. At least I can't remember right now why this wasn't done in
the first place.