* Re: Issue: regmap: use debugfs even when no device
[not found] <VI1PR0402MB3600F0FB1A031BE502588C93FF1E0@VI1PR0402MB3600.eurprd04.prod.outlook.com>
@ 2019-05-28 13:26 ` Mark Brown
2019-05-29 1:33 ` [EXT] " Andy Duan
0 siblings, 1 reply; 4+ messages in thread
From: Mark Brown @ 2019-05-28 13:26 UTC (permalink / raw)
To: Andy Duan; +Cc: david, rafael, Robby Cai, gregkh, linux-kernel
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On Tue, May 28, 2019 at 02:20:15AM +0000, Andy Duan wrote:
> So on i.MX8MM/8QM/8QXP platforms, we catch the issue that user dump regmap registers without
> power cause system hang.
> Maybe revert the patch is more reasonable ?
This is an issue with or without a device - you can have the same issue
with devices that are powered off. Typically where power is dynamic the
driver will use a register cache so the registers are always available.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: [EXT] Re: Issue: regmap: use debugfs even when no device
2019-05-28 13:26 ` Issue: regmap: use debugfs even when no device Mark Brown
@ 2019-05-29 1:33 ` Andy Duan
2019-05-29 11:15 ` Mark Brown
0 siblings, 1 reply; 4+ messages in thread
From: Andy Duan @ 2019-05-29 1:33 UTC (permalink / raw)
To: Mark Brown; +Cc: david, rafael, Robby Cai, gregkh, linux-kernel
From: Mark Brown <broonie@kernel.org> Sent: Tuesday, May 28, 2019 9:27 PM
> On Tue, May 28, 2019 at 02:20:15AM +0000, Andy Duan wrote:
>
> > So on i.MX8MM/8QM/8QXP platforms, we catch the issue that user dump
> > regmap registers without power cause system hang.
> > Maybe revert the patch is more reasonable ?
>
> This is an issue with or without a device - you can have the same issue with
> devices that are powered off. Typically where power is dynamic the driver
> will use a register cache so the registers are always available.
Correct, regmap without device also has issue when power if off, because regmap
doesn't implement runtime pm for the device, but maybe device driver implement
the runtime pm for the device.
So regmap how to manage the clock and power when access registers by debugfs ?
Andy
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [EXT] Re: Issue: regmap: use debugfs even when no device
2019-05-29 1:33 ` [EXT] " Andy Duan
@ 2019-05-29 11:15 ` Mark Brown
2019-05-30 4:56 ` Andy Duan
0 siblings, 1 reply; 4+ messages in thread
From: Mark Brown @ 2019-05-29 11:15 UTC (permalink / raw)
To: Andy Duan; +Cc: david, rafael, Robby Cai, gregkh, linux-kernel
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On Wed, May 29, 2019 at 01:33:46AM +0000, Andy Duan wrote:
> Correct, regmap without device also has issue when power if off, because regmap
> doesn't implement runtime pm for the device, but maybe device driver implement
> the runtime pm for the device.
> So regmap how to manage the clock and power when access registers by debugfs ?
Like I say the basic recommendation is to use a cache.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: [EXT] Re: Issue: regmap: use debugfs even when no device
2019-05-29 11:15 ` Mark Brown
@ 2019-05-30 4:56 ` Andy Duan
0 siblings, 0 replies; 4+ messages in thread
From: Andy Duan @ 2019-05-30 4:56 UTC (permalink / raw)
To: Mark Brown; +Cc: david, rafael, Robby Cai, gregkh, linux-kernel
From: Mark Brown <broonie@kernel.org> Sent: Wednesday, May 29, 2019 7:16 PM
> To: Andy Duan <fugang.duan@nxp.com>
> Cc: david@lechnology.com; rafael@kernel.org; Robby Cai
> <robby.cai@nxp.com>; gregkh@linuxfoundation.org; linux-kernel
> <linux-kernel@vger.kernel.org>
> Subject: Re: [EXT] Re: Issue: regmap: use debugfs even when no device
>
> On Wed, May 29, 2019 at 01:33:46AM +0000, Andy Duan wrote:
>
> > Correct, regmap without device also has issue when power if off,
> > because regmap doesn't implement runtime pm for the device, but maybe
> > device driver implement the runtime pm for the device.
>
> > So regmap how to manage the clock and power when access registers by
> debugfs ?
>
> Like I say the basic recommendation is to use a cache.
Got it, thanks.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-05-28 13:26 ` Issue: regmap: use debugfs even when no device Mark Brown
2019-05-29 1:33 ` [EXT] " Andy Duan
2019-05-29 11:15 ` Mark Brown
2019-05-30 4:56 ` Andy Duan
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