linux-kernel - RE: [PATCH 2.6.32 v2] MCP55 SATA2 conditional MSI support for sata

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Message-ID: <412A05BA40734D4887DBC67661F433080D7322B1@EXMAIL.ad.emulex.com>
Date:	Thu, 6 Aug 2009 09:28:02 -0700
From:	Chetan.Loke@...lex.Com
To:	<tony@...x.net>
CC:	<hancockrwd@...il.com>, <jgarzik@...ox.com>,
	<linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<philipl@...rt.org>
Subject: RE: [PATCH 2.6.32 v2] MCP55 SATA2 conditional MSI support for
 sata_nv

> -----Original Message-----
> From: Tony Vroon [mailto:tony@...x.net]
> Sent: Thursday, August 06, 2009 11:59 AM
> To: Loke,Chetan
> Cc: hancockrwd@...il.com; jgarzik@...ox.com; linux-ide@...r.kernel.org;
> linux-kernel@...r.kernel.org; philipl@...rt.org
> Subject: RE: [PATCH 2.6.32 v2] MCP55 SATA2 conditional MSI support for
> sata_nv
> 
> > disable_msi() is missing right?
> 
> I didn't add that as none of the other drivers have it:

Then they would leak the MSI-vectors if request_irq fails.


> chainsaw@...lthea /cvs/linux-2.6/drivers/ata $ grep _msi * | grep pci
> ahci.c:		pci_enable_msi(pdev);
> sata_mv.c:	if (msi && pci_enable_msi(pdev) == 0)
> sata_vsc.c:	if (pci_enable_msi(pdev) == 0)
> 
> (This is a tree without the sata_nv change I submitted)
> 
> I do believe it is safe to shut the interrupt down and unload the
> handler whilst it is still in MSI mode. At least, I don't see the libata
> core special-casing it in any way.

If I'm not wrong then that's how it's supposed to be done. free_irq and then disable_msi. You can't reverse the order. Also the driver should know when to quiesce the ASIC. So quiesce first and then shutdown everything.


> Regards,
> Tony V.

Regards
Chetan
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