Girish Shirasat wrote:
Hello All,
Thanks for your replies. If we see the dump, you will observe that
the NAND flash supports the MDMA2 but the driver does not set it but
goes in for PIO4. On looking at the ata_port_info structure populated
in case of 3100 SATA controller chipset namely the first entry, the
mwdma mask is not initialized causing the driver to skip the same and
go in for PIO modes. When I did add the MDMA mask, everything fell in
place and I was able to access the flash devices.
Can you please let me know if there is any specific reason as to
why the mdma masks are not added in the ata_port_info initialisations.
We are talking about AHCI, right?
Just an oversight IIRC. ISTR the original logic was somewhat of a
guess, since ahci.c was originally written in the early SATA days -- and
also admittedly when I understood less about SATA. I was worried about
controller snooping, and also did not think it would be needed to
support MWDMA, when UDMA was supported.
Obviously those were flawed trains of thought, in hindsight.
Jeff
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