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From: "zhao, forrest" <forrest.zhao@intel.com>
To: jeff@garzik.org
Cc: linux-ide@vger.kernel.org
Subject: A question about right-shift in ahci_port_start()
Date: Mon, 17 Apr 2006 15:25:53 +0800	[thread overview]
Message-ID: <1145258753.3417.5.camel@forrest26.sh.intel.com> (raw)

Hi, Jeff

When reading ahci_port_start(), I found the
following code segments:

.......
if (hpriv->cap & HOST_CAP_64)
        writel((pp->cmd_slot_dma >> 16) >> 16, port_mmio +
PORT_LST_ADDR_HI);
        writel(pp->cmd_slot_dma & 0xffffffff, port_mmio +
PORT_LST_ADDR);
        readl(port_mmio + PORT_LST_ADDR); /* flush */
......

I can't figure out why you use ">>16>>16" instead of
">>32" for right-shift 32 bits.

Would you please give me some hint?

Thanks,
Forrest

             reply	other threads:[~2006-04-17  7:36 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-04-17  7:25 zhao, forrest [this message]
2006-04-17  7:46 ` A question about right-shift in ahci_port_start() Tejun Heo

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