sata_mv wait for empty+idle (9b2c4e0b) · Commits · 戴 / test

When performing EH, it is recommended to wait for the EDMA engine to empty out requests-in-progress before disabling EDMA. Introduce code to poll the EDMA_STATUS register for idle/empty bits before disabling EDMA. For non-EH operation, this will normally exit without delay, other than the register read. A later series of patches may focus on eliminating this and various other register reads (when possible) throughout the driver, but for now we're focussing on solid reliablity. Signed-off-by:

Mark Lord <mlord@pobox.com> Signed-off-by:

Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_mv.c

+20 −0

Original line number	Diff line number	Diff line
		@@ -888,6 +888,25 @@ static void mv_start_dma(struct ata_port ap, void __iomem port_mmio,
		}
		}

		static void mv_wait_for_edma_empty_idle(struct ata_port *ap)
		{
		void __iomem *port_mmio = mv_ap_base(ap);
		const u32 empty_idle = (EDMA_STATUS_CACHE_EMPTY \| EDMA_STATUS_IDLE);
		const int per_loop = 5, timeout = (15 * 1000 / per_loop);
		int i;

		/*
		* Wait for the EDMA engine to finish transactions in progress.
		*/
		for (i = 0; i < timeout; ++i) {
		u32 edma_stat = readl(port_mmio + EDMA_STATUS_OFS);
		if ((edma_stat & empty_idle) == empty_idle)
		break;
		udelay(per_loop);
		}
		/* ata_port_printk(ap, KERN_INFO, "%s: %u+ usecs\n", __func__, i); */
		}

		/**
		* mv_stop_edma_engine - Disable eDMA engine
		* @port_mmio: io base address
		@@ -920,6 +939,7 @@ static int mv_stop_edma(struct ata_port *ap)
		if (!(pp->pp_flags & MV_PP_FLAG_EDMA_EN))
		return 0;
		pp->pp_flags &= ~MV_PP_FLAG_EDMA_EN;
		mv_wait_for_edma_empty_idle(ap);
		if (mv_stop_edma_engine(port_mmio)) {
		ata_port_printk(ap, KERN_ERR, "Unable to stop eDMA\n");
		return -EIO;

Admin message