linux-kernel - Re: [PATCH 14/36] ARM: OMAP2+: gpmc: Allow drivers to reconfigure GPMC settings & timings

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Date:	Fri, 13 Jun 2014 10:44:37 +0300
From:	Roger Quadros <rogerq@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	<dwmw2@...radead.org>, <computersforpeace@...il.com>,
	<kyungmin.park@...sung.com>, <pekon@...com>,
	<ezequiel.garcia@...e-electrons.com>, <javier@...hile0.org>,
	<nsekhar@...com>, <linux-omap@...r.kernel.org>,
	<linux-mtd@...ts.infradead.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 14/36] ARM: OMAP2+: gpmc: Allow drivers to reconfigure
 GPMC settings & timings

On 06/13/2014 10:25 AM, Tony Lindgren wrote:
> * Roger Quadros <rogerq@...com> [140611 01:58]:
>> Some devices (e.g. TUSB6010, omap-onenand) need to reconfigure the GPMC
>> timings in order to operate with different peripheral clock frequencies.
>> Introduce omap_gpmc_retime() to allow them to do that. The driver
>> needs to pass the chips select number, GPMC settings and Device timings to
>> omap_gpmc_retime().
>>
>> NOTE: Device tree and board code must still pass the most conservative
>> timings to GPMC so that the device can be probed by the respective driver.
>> e.g. Onenand must operate in asynchronous mode at bootup. The device driver
>> can then request for more optimal timings via omap_gpmc_retime().
> 
> Hmm but many of the devices are Linux generic like sms91x and 8250 so it's
> not nice to start stuffing omap bus specific data there.

Those drivers should never need to use this function. Hopefully they will work with a one time setup where we specify the timings in the DT. This function is primarily for use by omap-onenand and tusb6010, which are both OMAP specific.

cheers,
-roger

> 
> I wonder if we should just keep device specific gpmc-smc91x.c etc
> in drivers/memory?
> 
> Regards,
> 
> Tony
> 

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