libata: ahci_start_engine compliant to AHCI spec (270dac35) · Commits · 戴 / test

At the end of section 10.1 of AHCI spec (rev 1.3), it states Software shall not set PxCMD.ST to 1 until it is determined that a functoinal device is present on the port as determined by PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h Even though most AHCI host controller works without this check, specific controller will fail under this condition. Signed-off-by:

Jian Peng <jipeng2005@gmail.com> Signed-off-by:

Jeff Garzik <jgarzik@pobox.com>

drivers/ata/libahci.c

+21 −0

Original line number	Diff line number	Diff line
		@@ -561,6 +561,27 @@ void ahci_start_engine(struct ata_port *ap)
		{
		void __iomem *port_mmio = ahci_port_base(ap);
		u32 tmp;
		u8 status;

		status = readl(port_mmio + PORT_TFDATA) & 0xFF;

		/*
		* At end of section 10.1 of AHCI spec (rev 1.3), it states
		* Software shall not set PxCMD.ST to 1 until it is determined
		* that a functoinal device is present on the port as determined by
		* PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h
		*
		* Even though most AHCI host controllers work without this check,
		* specific controller will fail under this condition
		*/
		if (status & (ATA_BUSY \| ATA_DRQ))
		return;
		else {
		ahci_scr_read(&ap->link, SCR_STATUS, &tmp);

		if ((tmp & 0xf) != 0x3)
		return;
		}

		/* start DMA */
		tmp = readl(port_mmio + PORT_CMD);

Admin message