Erase granularity not set correctly on non-uniform flash

[davidk88]

Hello,

I'm using S25FL127S which does not support uniform 4k erase.

Library correctly reports via SFDP that flash chip does not supports uniform 4k erase, but it sets erase_gran and erase_gran_cmd to 4k erase anyway.

I modified library in such way that if sfdp.4k_erase is 0 then erase_gran and erase_gran_cmd is set to first eraser size which is larger than 4k, but I'm not sure if this is the correct way. I also dif not find any flags in SFDP that would tell which erase size is uniform for whole device.

Best regards

[armink]

Yes, when an unsupported erase size is found, and the erase size can be enlarged. You can submit your changes by PR.