linux-kernel - Re: [PATCH v2 2/2] mtd: nand: raw: gpmi: improve power management handling

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Message-ID: <20241003200508.x7tbf2lpbg6ngm7q@cozumel>
Date: Thu, 3 Oct 2024 15:05:08 -0500
From: Han Xu <han.xu@....com>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>, imx@...ts.linux.dev,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] mtd: nand: raw: gpmi: improve power management
 handling

On 24/10/03 05:28PM, Miquel Raynal wrote:
> Hi Han,
> 
> han.xu@....com wrote on Thu, 3 Oct 2024 10:05:16 -0500:
> 
> > On 24/10/03 09:38AM, Miquel Raynal wrote:
> > > Hi Han,
> > > 
> > > han.xu@....com wrote on Wed,  2 Oct 2024 10:39:44 -0500:
> > >   
> > > > The commit refactors the power management handling in the gpmi nand
> > > > driver. It removes redundant pm_runtime calls in the probe function,
> > > > handles the pad control in suspend and resume, and moves the calls to
> > > > acquire and release DMA channels to the runtime suspend and resume
> > > > functions.  
> > > 
> > > May I know the motivation to acquire and release the DMA channels
> > > during suspend? In general it seems like a different change which I'd
> > > prefer to see in its own commit with a justification. The rest looks
> > > ok otherwise.  
> > 
> > Hi Miquel,
> > 
> > Thanks for your comments. IMHO there is no much logic changes indeed, just move
> > the dma channel acquire and release from system pm to the runtime pm, releasing
> > the unused resources as early as possible. If you think it's necessary I will
> > split the patch into two parts.
> 
> Actually I don't understand why these channels are released and
> acquired again. Does it make sense to do that in the (runtime)
> suspend/resume path? I'd be in favor of avoiding this extra
> configuration which as a first sight does not seem required here.

Our local mxs-dma driver (will upstream the changes later) implemented the runtime
resume/suspend in channel alloc/release functions, so I did this in the gpmi
nand driver suspend/resume path.

> 
> Thanks,
> Miquèl