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

[Simon Glass]

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.

Regards,
Simon

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