On 28/10/15 07:03, Vinod Koul wrote:
> On Fri, Oct 16, 2015 at 09:25:52AM +0100, Jon Hunter wrote:
>> @@ -1182,14 +1182,11 @@ static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
>> {
>> struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>> struct tegra_dma *tdma = tdc->tdma;
>> - int ret;
>>
>> dma_cookie_init(&tdc->dma_chan);
>> tdc->config_init = false;
>> - ret = clk_prepare_enable(tdma->dma_clk);
>> - if (ret < 0)
>> - dev_err(tdc2dev(tdc), "clk_prepare_enable failed: %d\n", ret);
>> - return ret;
>> +
>> + return pm_runtime_get_sync(tdma->dev);
>
> Alloc channel is supposed to return number of descriptors allocated and if
> pm_runtime_get_sync() returns postive values we get wrong return!
Yes I will fix. I assume that returning 0 is allowed if no descriptors
are allocated here. So much for correcting rpm usage ;-)
>> pm_runtime_enable(&pdev->dev);
>> - if (!pm_runtime_enabled(&pdev->dev)) {
>> + if (!pm_runtime_enabled(&pdev->dev))
>> ret = tegra_dma_runtime_resume(&pdev->dev);
>> - if (ret) {
>> - dev_err(&pdev->dev, "dma_runtime_resume failed %d\n",
>> - ret);
>> - goto err_pm_disable;
>> - }
>> - }
>> + else
>> + ret = pm_runtime_get_sync(&pdev->dev);
>
> do we need pm_runtime_get() here, should we use pm_request_resume() ?
We definitely want pm_runtime_get_sync() because pm_request_resume() is
an ASYNC resume and so does not guarantee the device is accessible after
the call returns. The pm_runtime_get variant is nice too because it
keeps track of the number of gets and puts that have occurred.
>> static int tegra_dma_pm_suspend(struct device *dev)
>> {
>> struct tegra_dma *tdma = dev_get_drvdata(dev);
>> - int i;
>> - int ret;
>> + int i, ret;
>>
>> /* Enable clock before accessing register */
>> - ret = tegra_dma_runtime_resume(dev);
>> + ret = pm_runtime_get_sync(dev);
>
> If you are runtime suspended then core will runtime resume you before
> invoking suspend, so why do we need this
Is this change now in the mainline? Do you have commit ID for that?
I recall the last time we discussed this that Rafael said that they were
going to do that, but he said as a rule of thumb if you need to resume
it, resume it [0].
Cheers
Jon
[0] https://lkml.org/lkml/2015/8/24/845
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