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SubjectRe: [PATCH 1/1] libata: ahci_start_engine compliant to AHCI spec
Hello.

On 23-04-2011 10:58, Jian Peng wrote:

> 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,

"Most" requires plural noun, no?

> specific controller will fail under this condition.

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

> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 26d4523..83ed544 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -539,6 +539,27 @@ 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;

Masking is not necessary.

> +
> + /*
> + * 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,

Same about grammar here.

> + * specific controller will fail under this condition
> + */
> + if (status& (ATA_BUSY | ATA_DRQ))
> + return;
> + else {

{} should be used on both branches, according to CodingStyle.

WBR, Sergei


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