[PATCH V17 2/3] dmaengine: qcom_hidma: add debugfs hooks
okaya at codeaurora.org
Tue Apr 26 09:55:18 PDT 2016
On 4/26/2016 12:25 PM, Vinod Koul wrote:
> On Tue, Apr 26, 2016 at 08:08:16AM -0400, okaya at codeaurora.org wrote:
>> On 2016-04-25 23:30, Vinod Koul wrote:
>>> On Mon, Apr 11, 2016 at 10:21:12AM -0400, Sinan Kaya wrote:
>>>> +static int hidma_chan_stats(struct seq_file *s, void *unused)
>>>> + struct hidma_chan *mchan = s->private;
>>>> + struct hidma_desc *mdesc;
>>>> + struct hidma_dev *dmadev = mchan->dmadev;
>>>> + pm_runtime_get_sync(dmadev->ddev.dev);
>>> debug shouldn't power up device, why do you want to do that
>> Clocks are turned off while the hw is idle. I can’t reach hw
>> registers without restoring power.
> Hmm, have you thought about using regmap?
To be honest, I didn't know what regmap is but I just read some code
and looked at how it is used. Feel free to correct me if I got it
Regmap seems to be designed for *slow* speed peripherals to improve frequent
accesses by the SW. It looks like it is used by MFD, SPI and I2C drivers.
It seems to cache the register contents and flush/invalidate them only when
The MMIO version seems to be assuming the presence of device-tree like CLK
API which doesn't exist on ACPI systems and is not portable.
My reaction is that it is a lot of code with no added functionality to what
HIDMA driver is trying to achieve.
Given that the use case here is only for debug purposes; I think it is OK
to keep this runtime call here. I don't want to add any overhead into the
existing code just to support the debug use case.
None of my register read/writes are slow. This file will only be used to
troubleshoot customer issues.
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