Re: [PATCH 1/1] libata: ahci_start_engine compliant to AHCI spec

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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@xxxxxxxxx>
[...]

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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