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

[Jagan Teki]

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?

Thanks,
Jagan.

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