linux-kernel - Re: [PATCH] mfd:rtsx: Support RTS5249

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Date:	Mon, 25 Mar 2013 14:23:45 +0800
From:	wwang <wei_wang@...lsil.com.cn>
To:	Dan Carpenter <dan.carpenter@...cle.com>
CC:	<cjb@...top.org>, <sameo@...ux.intel.com>,
	<gregkh@...uxfoundation.org>, <linux-mmc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <rogerable@...ltek.com>,
	<devel@...uxdriverproject.org>
Subject: Re: [PATCH] mfd:rtsx: Support RTS5249

于 2013年03月25日 14:00, Dan Carpenter 写道:
> On Mon, Mar 25, 2013 at 10:13:56AM +0800, wei_wang@...lsil.com.cn wrote:
>> +static int rts5249_optimize_phy(struct rtsx_pcr *pcr)
>> +{
>> +	int err;
>> +
>> +	err = rtsx_pci_write_phy_register(pcr, 0x19, 0xFE46);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	mdelay(1);
> Why do we have the mdelay() and the later msleep(5)?
> rtsx_pci_write_phy_register() busy loops until the write succeeds or
> it returns -ETIMEOUT.  The extra wait here seems unnecessary.
>
> regards,
> dan carpenter
>
>
> .
>   

Hi,

The busy loops in rtsx_pci_write_phy_register only tell us that the 
write sequence succeeds. The device still needs to wait for a while 
until the internal signal stable. Or else the timing won't fit the 
requirement.
All of the delays in the driver are necessary.

BR,
Wei
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