linux-kernel - Re: [loongson-PATCH-v1 24/27] fixup for FUJITSU disk

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Message-Id: <200905231347.34717.bzolnier@gmail.com>
Date:	Sat, 23 May 2009 13:47:34 +0200
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	yanh@...ote.com
Cc:	wuzhangjin@...il.com, linux-mips@...ux-mips.org,
	Ralf Baechle <ralf@...ux-mips.org>,
	"IDE/ATA development list" <linux-ide@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"linux-scsi" <linux-scsi@...r.kernel.org>,
	Philippe Vachon <philippe@...pig.ca>,
	Zhang Le <r0bertz@...too.org>,
	Zhang Fuxin <zhangfx@...ote.com>,
	Arnaud Patard <apatard@...driva.com>,
	loongson-dev@...glegroups.com, gnewsense-dev@...gnu.org,
	Nicholas Mc Guire <hofrat@...r.at>,
	Liu Junliang <liujl@...ote.com>,
	Erwan Lerale <erwan@...scow.com>
Subject: Re: [loongson-PATCH-v1 24/27] fixup for FUJITSU disk

On Saturday 23 May 2009 09:11:42 yanh wrote:
> 在 2009-05-22五的 20:32 +0200，Bartlomiej Zolnierkiewicz写道：
> > On Thursday 21 May 2009 00:12:46 wuzhangjin@...il.com wrote:
> > > From: Wu Zhangjin <wuzhangjin@...il.com>
> > > 
> > > This is originally from the to-mips branch from
> > > http://dev.lemote.com/code/linux_loongson
> > 
> > Sadly, the patch description lacks all the important information.
> > 
> > What is the original problem that this fixup tries to address?
> > 
> > Is it limited to amd74xx controllers?
> 
> In loongson2f yeeloong machines, the ide controller is AMD cs5536, or
> say  amd74xx, and the hard drives is Fujistu. 

Then it should use the new & shiny :) native cs5536 IDE host driver
instead of legacy support in amd74xx...

> While debuging the hard disk suspned and resume, the ide irq can not be
> cleared. I guess this is a fake interrupt, hence the clear irq action
> can not be finished. 

AFAICS the only change that the fixup would cause for suspend/resume paths
is the one in ide_config_drive_speed() which is called during resume to set
transfer mode on the drive:

       tp_ops->write_devctl(hwif, ATA_NIEN | ATA_DEVCTL_OBS);

        memset(&tf, 0, sizeof(tf));
        tf.feature = SETFEATURES_XFER;
        tf.nsect   = speed;

        tp_ops->tf_load(drive, &tf, IDE_VALID_FEATURE | IDE_VALID_NSECT);

        tp_ops->exec_command(hwif, ATA_CMD_SET_FEATURES);
--->
        if (drive->quirk_list == 2)
                tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
--->
        error = __ide_wait_stat(drive, drive->ready_stat,
                                ATA_BUSY | ATA_DRQ | ATA_ERR,
                                WAIT_CMD, &stat);

Please tell me I if understand the issue correctly: if the above quirk is
not executed we end up with spurious IRQs, right?

> This patch is to fix this issue. Maybe other controller and drives also
> have this issue, but I am not sure.

Probably moving it to a generic quirk_drives list later will be useful...

Anyway this fixup needs to be ported to / verified with cs5536 first.

Thanks.
Bart
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