From: Jens Axboe <axboe@suse.de>
To: "zhao, forrest" <forrest.zhao@intel.com>
Cc: jeff@garzik.org, hare@suse.de, htejun@gmail.com, jeremy@goop.org,
lkml@rtr.ca, linux-ide@vger.kernel.org
Subject: Re: [PATCH 2/6] The definition of ahci_start_fis_rx() and ahci_stop_fis_rx()
Date: Fri, 2 Jun 2006 11:15:44 +0200 [thread overview]
Message-ID: <20060602091544.GA4400@suse.de> (raw)
In-Reply-To: <1149234295.13451.54.camel@forrest26.sh.intel.com>
On Fri, Jun 02 2006, zhao, forrest wrote:
> + /*
> + * Disable FIS reception
> + *
> + * AHCI Rev 1.1 Section 10.1.2:
> + * If PxCMD.FRE is set to '1', software should clear it
> + * to '0' and wait at least 500 milliseconds for PxCMD.FR
> + * to return '0' when read. If PxCMD.FR does not clear
> + * '0' correctly, then software may attempt a port reset
> + * of a full HBA reset to recover.
> + */
> + tmp &= ~(PORT_CMD_FIS_RX);
> + writel(tmp, port_mmio + PORT_CMD);
> +
> + mdelay(500);
> + work = 1000;
The spec states that you should wait up to 500msec for this condition to
happen, not wait 500msec before looking at it! So please rework this
bit, a half second potentially wasted busy loop is quite nasty.
Other than that, this part looks good too. If you fix it up, I can add
my signed-off to this bit as well.
--
Jens Axboe
next prev parent reply other threads:[~2006-06-02 9:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-02 7:44 [PATCH 2/6] The definition of ahci_start_fis_rx() and ahci_stop_fis_rx() zhao, forrest
2006-06-02 8:08 ` Hannes Reinecke
2006-06-02 9:15 ` Jens Axboe [this message]
2006-06-02 9:09 ` zhao, forrest
2006-06-02 9:26 ` Jens Axboe
2006-06-02 9:21 ` zhao, forrest
2006-06-03 12:51 ` Tejun Heo
2006-06-03 19:10 ` Jeff Garzik
-- strict thread matches above, loose matches on Subject: below --
2006-06-06 10:16 zhao, forrest
2006-06-29 8:18 zhao, forrest
2006-07-10 3:35 zhao, forrest
2006-07-10 17:08 ` Jens Axboe
2006-07-11 6:37 zhao, forrest
2006-07-13 5:38 zhao, forrest
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