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[PATCH] ahci: simplify ahci_start_engine()

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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>
This commit is contained in:
Tejun Heo 2006-07-26 15:59:26 +09:00 committed by Jeff Garzik
parent d8fcd116d2
commit 9f5920567b
1 changed files with 2 additions and 19 deletions
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21
drivers/scsi/ahci.c
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@ -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)