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SubjectRe: [PATCH v3] dmaengine: Add basic debugfs support
Hi Peter,

On 26-02-20, 14:10, Peter Ujfalusi wrote:

> > do we really want a custom dbg_show()..? Drivers can add their own
> > files...
>
> They could do that already ;)
>
> With the custom dbg_show() DMA drivers can save on the surrounding
> code and just fill in the information regarding to their HW.
> Again, on am654 the default information is:
> # cat /sys/kernel/debug/dmaengine
> dma0 (285c0000.dma-controller): number of channels: 96
>
> dma1 (31150000.dma-controller): number of channels: 267
> dma1chan0 | 2b00000.mcasp:tx
> dma1chan1 | 2b00000.mcasp:rx
> dma1chan2 | in-use
> dma1chan3 | in-use
> dma1chan4 | in-use
> dma1chan5 | in-use
>
> With my current .dbg_show implementation for k3-udma:
> # cat /sys/kernel/debug/dmaengine
> dma0 (285c0000.dma-controller): number of channels: 96
>
> dma1 (31150000.dma-controller): number of channels: 267
> dma1chan0 | 2b00000.mcasp:tx (MEM_TO_DEV, tchan8 [0x1008 -> 0xc400], PDMA, TR mode)
> dma1chan1 | 2b00000.mcasp:rx (DEV_TO_MEM, rchan8 [0x4400 -> 0x9008], PDMA, TR mode)
> dma1chan2 | in-use (MEM_TO_MEM, chan2 pair [0x1002 -> 0x9002], PSI-L Native, TR mode)
> dma1chan3 | in-use (MEM_TO_MEM, chan3 pair [0x1003 -> 0x9003], PSI-L Native, TR mode)
> dma1chan4 | in-use (MEM_TO_MEM, chan4 pair [0x1004 -> 0x9004], PSI-L Native, TR mode)
> dma1chan5 | in-use (MEM_TO_MEM, chan5 pair [0x1005 -> 0x9005], PSI-L Native, TR mode)
>
> For me this makes a huge difference.

Ok

> >> +DEFINE_SHOW_ATTRIBUTE(dmaengine_debugfs);
> >> +
> >> +static int __init dmaengine_debugfs_init(void)
> >> +{
> >> + /* /sys/kernel/debug/dmaengine */
> >> + debugfs_create_file("dmaengine", 0444, NULL, NULL,
> >> + &dmaengine_debugfs_fops);
> >
> > Should we add a directory? That way we can keep adding stuff into that
> > one
>
> and have this file as 'summary' underneath?

Correct

> I like the fact hat I can get all the information via one file.
> Saves a lot of time (and explaining to users) on finding the correct
> one to cat...

But am sure we can come with more data to show, so having a directory
helps :)

--
~Vinod

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