linux-kernel - Re: [RESEND PATCH v7] mtd: spi-nor: add hisilicon spi-nor flash controller driver

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Date:	Wed, 9 Mar 2016 11:35:57 +0800
From:	Jiancheng Xue <xuejiancheng@...wei.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:	Brian Norris <computersforpeace@...il.com>, <robh+dt@...nel.org>,
	<pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<dwmw2@...radead.org>, <zajec5@...il.com>, <jteki@...nedev.com>,
	<ezequiel@...guardiasur.com.ar>, <juhosg@...nwrt.org>,
	<shijie.huang@...el.com>, <mika.westerberg@...ux.intel.com>,
	<furquan@...gle.com>, <han.xu@...escale.com>,
	<fabio.estevam@...escale.com>, <manabian@...il.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-mtd@...ts.infradead.org>, <yanhaifeng@...ilicon.com>,
	<yanghongwei@...ilicon.com>, <suwenping@...ilicon.com>,
	<raojun@...ilicon.com>, <ml.yang@...ilicon.com>,
	<gaofei@...ilicon.com>, <zhangzhenxing@...ilicon.com>,
	<xuejiancheng@...ilicon.com>, Binquan Peng <pengbinquan@...wei.com>
Subject: Re: [RESEND PATCH v7] mtd: spi-nor: add hisilicon spi-nor flash
 controller driver

Hi Boris,

On 2016/3/8 17:46, Boris Brezillon wrote:
>> [...]
>>>> +static int hisi_spi_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
>>>> +		int len)
>>>> +{
>>>> +	struct hifmc_priv *priv = nor->priv;
>>>> +	struct hifmc_host *host = priv->host;
>>>> +	int ret;
>>>> +
>>>> +	ret = hisi_spi_nor_send_cmd(nor, opcode, len);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	memcpy(buf, host->iobase, len);
>>>
>>> sparse doesn't like any of these memcpy()'s, since that's __iomem. Are
>>> you sure you want a regular memcpy here, and elsewhere?
>>>
>> It's not a must to use memcpy though host->iobase represents a segment of inner memory
>> which stores data from flash device byte by byte.  I will give up using memcpy here and
>> hisi_spi_nor_write_reg() in next version. Thank you!
> 
> Or you can use memcpy_fromio(), which should give you better perfs than
> using readX() accessors in a loop.
> 

Thank you very much for your suggestion. I'll look into sparse and this function.

Regards,
Jiancheng