Re: [PATCH] OMAP: fix gpmc nand setup when no timings supplied

[Mike Rapoport <mike@compulab.co.il>]

Ghorai, Sukumar wrote:
> 
>> -----Original Message-----
>> From: Mike Rapoport [mailto:mike@compulab.co.il]
>> Sent: 2010-04-22 12:29
>> To: Ghorai, Sukumar
>> Cc: linux-omap@vger.kernel.org; Tony Lindgren
>> Subject: Re: [PATCH] OMAP: fix gpmc nand setup when no timings supplied
>>
>> Ghorai, Sukumar wrote:
>>>> -----Original Message-----
>>>> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
>>>> owner@vger.kernel.org] On Behalf Of Mike Rapoport
>>>> Sent: 2010-04-22 10:50
>>>> To: linux-omap@vger.kernel.org
>>>> Cc: Tony Lindgren; Mike Rapoport
>>>> Subject: Re: [PATCH] OMAP: fix gpmc nand setup when no timings supplied
>>>>
>>>> Any comments on this?
>>>>
>>>> Mike Rapoport wrote:
>>>>> The gpmc nand infrastructure crashes when there no timing structure
>>>>> supplied in the omap_nand_platform_data. Adding check for
>>>>> gpmc_nand_data->gpmc_t pointer validity resolves the crash and allows
>> to
>>>>> continue nand initialization without modifying gpmc timings.
>>>>>
>>>>> Signed-off-by: Mike Rapoport <mike@compulab.co.il>
>>>>> ---
>>>>>  arch/arm/mach-omap2/gpmc-nand.c |    5 +++++
>>>>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm/mach-omap2/gpmc-nand.c b/arch/arm/mach-
>> omap2/gpmc-
>>>> nand.c
>>>>> index 64d74f0..3629da3 100644
>>>>> --- a/arch/arm/mach-omap2/gpmc-nand.c
>>>>> +++ b/arch/arm/mach-omap2/gpmc-nand.c
>>>>> @@ -83,6 +83,11 @@ static int gpmc_nand_setup(void)
>>>>>  {
>>>>>  	struct device *dev = &gpmc_nand_device.dev;
>>>>>
>>>>> +	if (!gpmc_nand_data->gpmc_t) {
>>>>> +		dev_info(dev, "Keeping gpmc timings\n");
>>>>> +		return 0;
>>>>> +	}
>>> [Ghorai] This is the only time its setup the gpmc timings for NAND. And
>> it should return as error.
>>
>> Somehow I was under the impression that X-Loader sets up the NAND
>> timings even if booted from OneNAND or MMC. Apparently I'm wrong :).
>>
>> What do you think about adding a flag to omap_nand_platform_data that
>> will allow to keep timings if they were already configured by the
>> bootloader? This is really useful when the board can be assembled with
>> different kinds of NAND flashes.
> [Ghorai] firstly we should not depend on u-boot/ x-loader for this GPMC configuration.
 > I think each board will have only one device finally.

CM-T35, for instance can be assembled with different NAND flash chips. 
Besides, boards that use NAND as primary boot device, we anyway depend 
on proper GPMC configuration in the bootloader chain. Having ability to 
define GPMC timings in the kernel and keep the settings made by the 
bootloader adds flexibility level for board designers.

>>>>> +
>>>>>  	/* Set timings in GPMC */
>>>>>  	if (omap2_nand_gpmc_retime() < 0) {
>>>>>  		dev_err(dev, "Unable to set gpmc timings\n");
>>>> --
>>>> Sincerely yours,
>>>> Mike.
>>>> --
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>>
>> --
>> Sincerely yours,
>> Mike.


-- 
Sincerely yours,
Mike.