Hi Michael,
On 22.05.2010 01:38, Carl-Daniel Hailfinger wrote:
> On 25.03.2010 10:46, Michael Karcher wrote:
>
>> Am Donnerstag, den 25.03.2010, 03:10 +0100 schrieb Carl-Daniel
>> Hailfinger:
>>
>>
>>> + /* Warning: This loop has a very unusual condition and body.
>>> + * The loop needs to go through each page with at least one affected
>>> + * byte. The lowest page number is (start / page_size) since that
>>> + * division rounds down. The highest page number we want is the page
>>> + * where the last byte of the range lives. That last byte has the
>>> + * address (start + len - 1), thus the highest page number is
>>> + * (start + len - 1) / page_size. Since we want to include that last
>>> + * page as well, the loop condition uses <=.
>>> + */
>>> + for (i = start / page_size; i <= (start + len - 1) / page_size; i++) {
>>> + /* Byte position of the first byte in the range in this page. */
>>> + /* starthere is an offset to the base address of the chip. */
>>> + starthere = max(start, i * page_size);
>>> + /* Length of bytes in the range in this page. */
>>> + lenhere = min(start + len, (i + 1) * page_size) - starthere;
>>> + for (j = 0; j < lenhere; j += chunksize) {
>>> + towrite = min(chunksize, lenhere - j);
>>> + rc = spi_nbyte_program(starthere + j, buf + starthere -
>>> start + j, towrite);
>>> + if (rc)
>>> + break;
>>> + while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
>>> + programmer_delay(10);
>>> + }
>>> + if (rc)
>>> + break;
>>> + }
>>>
>>>
>> i would write this as (carful, untested):
>>
>> startofs = start % pagesize; /* offset relative to page begin */
>> /* iterate over all pages to write */
>> for(pageaddr = start - startofs; pageaddr < start + len;
>> pageaddr += page_size) {
>> endofs = min(pagesize, start + len - pageaddr);
>> /* iterate over chunks in this page */
>> for(j = startofs; j < endofs; j += chunksize) {
>> towrite = min(chunksize, endofs - j);
>> rc = spi_nbyte_program(pageaddr + j, buf, towrite);
>> buf += towrite;
>> if (rc)
>> goto leave_page_loop;
>> /* Copy/paste wait here */
>> }
>> startofs = 0; /* all pages but the first need to be programmed
>> from the beginning */
>> }
>> leave_page_loop:
>>
>>
>
> If you could send your code as patch for spi_read_chunked and
> spi_write_chunked, I'd be really happy.
>
>
>
>> Your logic seem right, too, so this is a matter of taste. I think my
>> version needs less explanation, that's why I would prefer it that way.
>>
>>
>
> Fully agreed. We want your logic.
>
Could you send your logic as a patch which changes spi_read_chunked and
spi_write_chunked?
Thanks!
Regards,
Carl-Daniel
--
http://www.hailfinger.org/
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