On 4/26/2016 12:25 PM, Vinod Koul wrote: > On Tue, Apr 26, 2016 at 08:08:16AM -0400, okaya@xxxxxxxxxxxxxx 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 wrong. 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 needed. 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. -- Sinan Kaya Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html