linux-kernel - Re: [PATCH v3 1/6] mtd: nand: gpmi: add gpmi dsm supend/resume support

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Message-ID: <20150901081117.GA14749@free64-pc.asiapac.arm.com>
Date:	Tue, 1 Sep 2015 16:11:17 +0800
From:	Huang Shijie <shijie.huang@....com>
To:	Nicholas Mc Guire <der.herr@...r.at>
Cc:	Han Xu <b45815@...escale.com>, dwmw2@...radead.org,
	computersforpeace@...il.com, boris.brezillon@...e-electrons.com,
	fabio.estevam@...escale.com, hofrat@...dl.org,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	vinod.koul@...el.com, dan.j.williams@...el.com,
	dmaengine@...r.kernel.org
Subject: Re: [PATCH v3 1/6] mtd: nand: gpmi: add gpmi dsm supend/resume
 support

On Sat, Aug 29, 2015 at 11:17:40AM +0200, Nicholas Mc Guire wrote:
> On Fri, 28 Aug 2015, Han Xu wrote:
> 
> > From: Huang Shijie <b32955@...escale.com>
> > 
> > i.MX6SX supports deep sleep mode(DSM) that may turn off GPMI/BCH power
> > during suspend, add gpmi nand suspend/resume function to release DMA
> > channel in suspend function and re-init GPMI/BCH controller during
> > resume function.
> >
> 
> Just a question regarding gpmi_pm_resume() errror reporting
> Is there a reason that the retrun value of gpmi_extra_init() is not checked ?
> gpmi_extra_init() can retrun -ENOMEM or -EINVAL via return enable_edo_mode(),
> while the -EINVAL would produce a dev_err message, -ENOMEM does not so maybe
> this also wants to include a if(ret) {...} ? - something like the below
>  
> > Although it is not necessary to restore GPMI/BCH registers value for
> > i.MX6QDL, the code doesn't distinguish different platforms to keep the
> > code simple.
> > 
> > Signed-off-by: Huang Shijie <b32955@...escale.com>
> > Signed-off-by: Han Xu <han.xu@...escale.com>
> > ---
> >  drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 45 +++++++++++++++++++++++++++++++++-
> >  1 file changed, 44 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > index 1b8f350..dfd0ba1 100644
> > --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > @@ -1,7 +1,7 @@
> >  /*
> >   * Freescale GPMI NAND Flash Driver
> >   *
> > - * Copyright (C) 2010-2011 Freescale Semiconductor, Inc.
> > + * Copyright (C) 2010-2015 Freescale Semiconductor, Inc.
> >   * Copyright (C) 2008 Embedded Alley Solutions, Inc.
> >   *
> >   * This program is free software; you can redistribute it and/or modify
> > @@ -2036,9 +2036,52 @@ static int gpmi_nand_remove(struct platform_device *pdev)
> >  	return 0;
> >  }
> >  
> > +static int gpmi_pm_suspend(struct device *dev)
> > +{
> > +	struct gpmi_nand_data *this = dev_get_drvdata(dev);
> > +
> > +	release_dma_channels(this);
> > +	return 0;
> > +}
> > +
> > +static int gpmi_pm_resume(struct device *dev)
> > +{
> > +	struct gpmi_nand_data *this = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	ret = acquire_dma_channels(this);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	/* re-init the GPMI registers */
> > +	this->flags &= ~GPMI_TIMING_INIT_OK;
> > +	ret = gpmi_init(this);
> > +	if (ret) {
> > +		dev_err(this->dev, "Error setting GPMI : %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	/* re-init the BCH registers */
> > +	ret = bch_set_geometry(this);
> > +	if (ret) {
> > +		dev_err(this->dev, "Error setting BCH : %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	/* re-init others */
> > +	gpmi_extra_init(this);
> 
> report failure of enable_edo_mode() ?
> 
> 	if (ret) {
> 		dev_err(this->dev, "Error enabling EDO mode : %d\n", ret);
> 		return ret;
> 	}
I think it's better that we do not report the failure of the enable_edo_mode() here.
If we do so, the gpmi may cannot work when the enable_edo_mode() fails.

But if we do not report it, the gpmi still can work.

thanks
Huang Shijie

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