On Mon, 29 Oct 2007 22:17:40 -0600 Robert Hancock <hancockr@xxxxxxx> wrote: > In the sata_nv driver, when running in ADMA mode, we can do 64-bit DMA. > However, when an ATAPI device like a DVD drive is connected, we can't > use ADMA mode, and so we have to abide by the restrictions of a normal > SFF ATA controller and can only do 32-bit DMA. We detect this and try to > set the blk_queue_bounce_limit, blk_queue_segment_boundary and > blk_queue_max_hw_segments to the values corresponding to a normal SFF > controller. What about the DMA padding buffer from nv_adma_port_start and internal buffers for commands like request sense that don't come via the request queue directly. Also it seems nv_adma_use_reg_mode() can decide to send other commands via the non ADMA interface even for ATA devices. Are we 100% certain it never decides to let through a command with DMA via the register interface in this case - what do you see if you instrument the function ? Alan - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
