[U-Boot] [PATCH v2 08/15] sf: Respect maximum SPI write size

[Jagan Teki]

Hi Simon,

On Wed, Apr 24, 2013 at 2:43 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Jagan,
>
> On Tue, Apr 23, 2013 at 2:01 PM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>> Hi Simon,
>>
>> On Wed, Apr 24, 2013 at 2:20 AM, Simon Glass <sjg at chromium.org> wrote:
>>> Hi Jagan,
>>>
>>> On Tue, Apr 23, 2013 at 1:44 PM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>>> Hi Simon,
>>>>
>>>> On Mon, Mar 11, 2013 at 9:38 PM, Simon Glass <sjg at chromium.org> wrote:
>>>>> Some SPI flash controllers (e.g. Intel ICH) have a limit on the number of
>>>>> bytes that can be in a write transaction. Support this by breaking the
>>>>> writes into multiple transactions.
>>>>>
>>>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>>>> ---
>>>>> Changes in v2: None
>>>>>
>>>>>  drivers/mtd/spi/spi_flash.c | 10 ++++++++--
>>>>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
>>>>> index 17f3d3c..b82011d 100644
>>>>> --- a/drivers/mtd/spi/spi_flash.c
>>>>> +++ b/drivers/mtd/spi/spi_flash.c
>>>>> @@ -87,6 +87,9 @@ int spi_flash_cmd_write_multi(struct spi_flash *flash, u32 offset,
>>>>>         for (actual = 0; actual < len; actual += chunk_len) {
>>>>>                 chunk_len = min(len - actual, page_size - byte_addr);
>>>>>
>>>>> +               if (flash->spi->max_write_size)
>>>>> +                       chunk_len = min(chunk_len, flash->spi->max_write_size);
>>>>> +
>>>>>                 cmd[1] = page_addr >> 8;
>>>>>                 cmd[2] = page_addr;
>>>>>                 cmd[3] = byte_addr;
>>>>> @@ -111,8 +114,11 @@ int spi_flash_cmd_write_multi(struct spi_flash *flash, u32 offset,
>>>>>                 if (ret)
>>>>>                         break;
>>>>>
>>>>> -               page_addr++;
>>>>> -               byte_addr = 0;
>>>>> +               byte_addr += chunk_len;
>>>>> +               if (byte_addr == page_size) {
>>>>> +                       page_addr++;
>>>>> +                       byte_addr = 0;
>>>>> +               }
>>>>
>>>> Does this change required to handle < page_size writes, means if the
>>>> user is giving an offset other than
>>>> multiples of page_sizes?
>>>
>>> I'm not quite sure what you are saying, but let me try to response.
>>>
>>> I believe what should happen is that byte_addr should become aligned
>>> to the page_size after the first transfer, and from then on it should
>>> start at 0 for each page.
>>>
>>> Are you seeing a problem?
>>
>> My question,what if this change doesn't have.?
>> Can't I able to write data starts from unaligned page_sizes?
>
> It should work fine - I did in fact find a problem in the driver in
> this case, which I fixed. Let me know if you see any problem.

Means this change is for proper handling of write data starts from
unaligned page_sizes, is it?

Thanks,
Jagan.

>
> Regards,
> Simon
>
>>
>> Thanks,
>> Jagan.
>>
>>>
>>> Regards,
>>> Simon
>>>
>>>>
>>>> Thanks,
>>>> Jagan.