Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller

From: masonccyang@mxic.com.tw
To: "Miquel Raynal" <miquel.raynal@bootlin.com>
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
	christophe.kerello@st.com, bbrezillon@kernel.org,
	juliensu@mxic.com.tw, lee.jones@linaro.org,
	linux-kernel@vger.kernel.org, robh+dt@kernel.org,
	linux-spi@vger.kernel.org, marcel.ziswiler@toradex.com,
	paul.burton@mips.com, broonie@kernel.org, geert@linux-m68k.org,
	stefan@agner.ch, linux-mtd@lists.infradead.org, richard@nod.at,
	liang.yang@amlogic.com, computersforpeace@gmail.com,
	dwmw2@infradead.org, marek.vasut@gmail.com,
	zhengxunli@mxic.com.tw
Subject: Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller
Date: Fri, 17 May 2019 17:30:21 +0800	[thread overview]
Message-ID: <OF074A1F06.5C1A58BE-ON482583FD.0031CD95-482583FD.003437AD@mxic.com.tw> (raw)
In-Reply-To: <20190512151820.4f2dd9da@xps13>

Hi Miquel,

> > +
> > +static void mxic_nand_select_chip(struct nand_chip *chip, int chipnr)
> 
> _select_target() is preferred now

Do you mean I implement mxic_nand_select_target() to control #CS ?

If so, I need to call mxic_nand_select_target( ) to control #CS ON
and then #CS OFF in _exec_op() due to nand_select_target()<in nand_base,c>
is still calling chip->legacy.select_chip ?

> 
> > +{
> > +   struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> > +
> > +   switch (chipnr) {
> > +   case 0:
> > +   case 1:
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +      writel(HC_CFG_MAN_CS_ASSERT | readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> 
> In both case I would prefer a:
> 
>         reg = readl(...);
>         reg &= ~xxx;
>    reg |= yyy;
>    writel(reg, ...);
> 
> Much easier to read.
> 
> > +      break;
> > +
> > +   case -1:
> > +      writel(~HC_CFG_MAN_CS_ASSERT & readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      break;
> > +
> > +   default:
> 
> Error?
> 
> > +      break;
> > +   }
> > +}
> > +

> > +static int mx25f0a_nand_probe(struct platform_device *pdev)
> > +{
> > +   struct mtd_info *mtd;
> > +   struct mx25f0a_mfd *mfd = dev_get_drvdata(pdev->dev.parent);
> > +   struct mxic_nand_ctlr *mxic;
> > +   struct nand_chip *nand_chip;
> > +   int err;
> > +
> > +   mxic = devm_kzalloc(&pdev->dev, sizeof(struct mxic_nand_ctlr),
> > +             GFP_KERNEL);
> 
> mxic for a NAND controller structure is probably not a name meaningful
> enough.
> 
> > +   if (!mxic)
> > +      return -ENOMEM;
> > +
> > +   nand_chip = &mxic->nand;
> > +   mtd = nand_to_mtd(nand_chip);
> > +   mtd->dev.parent = pdev->dev.parent;
> > +   nand_chip->ecc.priv = NULL;
> > +   nand_set_flash_node(nand_chip, pdev->dev.parent->of_node);
> > +   nand_chip->priv = mxic;
> > +
> > +   mxic->mfd = mfd;
> > +
> > +   nand_chip->legacy.select_chip = mxic_nand_select_chip;
> 
> Please don't implement legacy interfaces. You can check in
> marvell_nand.c how this is handled now:
> 
> b25251414f6e mtd: rawnand: marvell: Stop implementing ->select_chip()
> 

Does it mean chip->legacy.select_chip() will phase-out ?

thanks & best regards,
Mason

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This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as its attachment(s) from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.

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