[PATCH] ahci: simplify ahci_start_engine() (9f592056) · Commits · 戴 / test

Simplify ahci_start_engine() by killing prerequisite condition checks. Rationales are.. * No user checks error return from ahci_start_engine() * Code flow guarantees the prerequisite conditions unless the controller is malfunctioning. In such cases, the driver had chances to learn about the problem _before_ calling this function. * Closely related to the above two, driver calls into this function even when prerequisites fail hoping for the best. Basically, ahci_start_engine() should only do the operation itself. It isn't the right place to check for prerequisites. Signed-off-by:

Tejun Heo <htejun@gmail.com> Signed-off-by:

Zhao, Forrest <forrest.zhao@intel.com> Signed-off-by:

Jeff Garzik <jeff@garzik.org>

drivers/scsi/ahci.c

+2 −19

Original line number	Diff line number	Diff line
		@@ -406,32 +406,15 @@ static void ahci_scr_write (struct ata_port *ap, unsigned int sc_reg_in,
		writel(val, (void __iomem ) ap->ioaddr.scr_addr + (sc_reg 4));
		}

		static int ahci_start_engine(void __iomem *port_mmio)
		static void ahci_start_engine(void __iomem *port_mmio)
		{
		u32 tmp;

		/* get current status */
		tmp = readl(port_mmio + PORT_CMD);

		/* AHCI rev 1.1 section 10.3.1:
		* Software shall not set PxCMD.ST to '1' until it verifies
		* that PxCMD.CR is '0' and has set PxCMD.FRE to '1'
		*/
		if ((tmp & PORT_CMD_FIS_RX) == 0)
		return -EPERM;

		/* wait for engine to become idle */
		tmp = ata_wait_register(port_mmio + PORT_CMD,
		PORT_CMD_LIST_ON, PORT_CMD_LIST_ON, 1,500);
		if (tmp & PORT_CMD_LIST_ON)
		return -EBUSY;

		/* start DMA */
		tmp = readl(port_mmio + PORT_CMD);
		tmp \|= PORT_CMD_START;
		writel(tmp, port_mmio + PORT_CMD);
		readl(port_mmio + PORT_CMD); /* flush */

		return 0;
		}

		static int ahci_stop_engine(void __iomem *port_mmio)

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