On 29/10/15 01:57, Vinod Koul wrote:
> On Wed, Oct 28, 2015 at 01:32:12PM +0000, Jon Hunter wrote:
>>
>> 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 ;-)
>
> Yes 0 is allowed...
>
>>>> 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].
>
> IIRC this has been always the behaviour, at least I see this when I test the
> devices
I have been doing some testing today and if the DMA is runtime
suspended, then I don't see it runtime resumed before suspend is called.
Can you elborate on "at least I see this when I test the devices"? What
are you looking at? Are you using kernel function tracers in some way?
Cheers
Jon
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