[PATCH V2 2/2] mtd: msm_nand: Add initial msm nand driver support.

[Murali Nalajala]

On 4/18/2011 1:02 PM, Matthieu CASTET wrote:
> Hi,
>
> Murali Nalajala a écrit :
>> Add initial msm nand driver support for Qualcomm MSM platforms.
>> This driver is capable of handling both 2k and 4k page support
>> nand devices.
>>
>> This driver was originally developed by Arve Hjønnevåg at google.
>> Its source is available at
>> http://android.git.kernel.org/?p=kernel/msm.git under
>> android-msm-2.6.35 branch.
>>
>> CC: Dima Zavin<dima at android.com>
>> CC: Brian Swetland<swetland at google.com>
>> CC: Arve Hjønnevåg<arve at android.com>
>> Signed-off-by: Murali Nalajala<mnalajal at codeaurora.org>
>> ---
>> Changes in V2
>> * Turn most of the pr_info() calls into pr_debug().
>>
>>   drivers/mtd/devices/Kconfig    |   11 +
>>   drivers/mtd/devices/Makefile   |    1 +
>>   drivers/mtd/devices/msm_nand.c | 1597 ++++++++++++++++++++++++++++++++++++++++
>>   drivers/mtd/devices/msm_nand.h |   77 ++
>>   4 files changed, 1686 insertions(+), 0 deletions(-)
>>   create mode 100644 drivers/mtd/devices/msm_nand.c
>>   create mode 100644 drivers/mtd/devices/msm_nand.h
>>
>
> For the record, I am not sure it is a great idea to make nand drivers
> independent of the nand layer.
> By doing that you could change the expected behavior, and introduce bug
> difficult to debug.
>
> Why do you need that ? Nand drivers can override callbacks of nand framework.
>
> Maybe because the nand layer call the driver page per page, and  you want to
> work with more than one page. But in this case you can extend nand layer.
>
> Or does your controller don't allow sending raw command ?
> And in that case all the nand logic is in the nand controller ?

Our controller doesn't allow sending RAW commands to the flash. All 
these commands are abstracted by the controller logic. Please refer the 
msm_nand.h file where you will find the commands which are different 
from the actual NAND device commands.

eg: To send read/write data command to the device we configure the 
controller with page address & controller specific command. Then the 
controller itself takes care of generating the internal h/w signals 
required by the flash and it polls for the R/B signal & wait states are 
internally controlled by the h/w.

>
> Matthieu



Thanks,
Murali N

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