On Mon, Jun 16, 2014 at 03:05:36PM +0530, Suman Tripathi wrote:
> This patch fixes the dma state machine lockup due to the IDENTIFY DEVICE PIO
> mode command. The controller is unable to clear the BSY bit after receiving
> the PIO setup FIS and results the dma state machine to go into the
> CMFatalErrorUpdate state resulting in the dma state machine lockup.
Ditto on description formatting and SOB. Also, please describe why
this patch is removing the restart from read_id.
> +int ahci_complete_pio_cmd(struct ata_port *ap, u32 cmd_done)
> +{
> + struct ata_queued_cmd *qc;
> +
> + while (cmd_done) {
> + unsigned int tag = __ffs(cmd_done);
> +
> + qc = ata_qc_from_tag(ap, tag);
> + if (qc) {
> + /*
> + * For the IDENTIFY DEVICE PIO command,
> + * some controller's unable to clear the BSY bit after
> + * receiving the PIO Setup FIS from device resulting
> + * the DMA state to go into CMFatalErrorUpdate state.
> + * So need to restart the dma engine to get the
> + * controller out of this state.
> + */
> + if (qc->tf.command == ATA_CMD_ID_ATA)
> + ahci_restart_engine(ap);
> + }
> + cmd_done &= ~(1 << tag);
> + }
> +
> + return 0;
> +}
> +
> static void ahci_error_intr(struct ata_port *ap, u32 irq_stat)
> {
> struct ahci_host_priv *hpriv = ap->host->private_data;
> @@ -1778,6 +1804,14 @@ static void ahci_handle_port_interrupt(struct ata_port
> *ap,
> }
>
>
> + /* Due to HW errata, some controllers need special handling
> + * of the completion of some PIO commands.
> + */
> + if (hpriv->flags & AHCI_HFLAG_BROKEN_PIO_CMD) {
> + u32 cmd_done = ap->qc_active ^ qc_active;
> + ahci_complete_pio_cmd(ap, cmd_done);
> + }
Heh, I feel this is a bit too specific to bury in libahci.c and don't
really like adding this sort workaround in the hot path for everybody.
Then again, ahci interrupt handler isn't exactly structured in a way
which is easy to wrap and create a custom one.
Does this have to happen from interrupt path tho? Can't you just
record the last protocol executed and restart the engine on the next
qc_issue?
Thanks.
--
tejun
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