linux-kernel - Re: [PATCH 03/17] hpsa: enable bus master bit after pci_enable

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Date:	Fri, 20 Apr 2012 12:41:50 -0600
From:	Khalid Aziz <khalid.aziz@...com>
To:	"Stephen M. Cameron" <scameron@...rdog.cce.hp.com>
Cc:	james.bottomley@...senpartnership.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, matthew.gates@...com,
	stephenmcameron@...il.com, thenzl@...hat.com,
	akpm@...ux-foundation.org, mikem@...rdog.cce.hp.com
Subject: Re: [PATCH 03/17] hpsa: enable bus master bit after
 pci_enable_device

On Fri, 2012-04-20 at 10:06 -0500, Stephen M. Cameron wrote:
> From: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
> 
> pci_disable_device() disables the bus master bit and pci_enable_device does
> not re-enable it.  It needs to be enabled.
> 
> Signed-off-by: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
> ---
>  drivers/scsi/hpsa.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 5119ce6..363619d 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -3917,6 +3917,7 @@ static int __devinit hpsa_enter_simple_mode(struct ctlr_info *h)
>  static int __devinit hpsa_pci_init(struct ctlr_info *h)
>  {
>  	int prod_index, err;
> +	u16 command_register;
>  
>  	prod_index = hpsa_lookup_board_id(h->pdev, &h->board_id);
>  	if (prod_index < 0)
> @@ -3933,6 +3934,11 @@ static int __devinit hpsa_pci_init(struct ctlr_info *h)
>  		return err;
>  	}
>  
> +	/* Enable bus mastering (pci_disable_device may disable this) */
> +	pci_read_config_word(h->pdev, PCI_COMMAND, &command_register);
> +	command_register |= PCI_COMMAND_MASTER;
> +	pci_write_config_word(h->pdev, PCI_COMMAND, command_register);
> +
>  	err = pci_request_regions(h->pdev, HPSA);
>  	if (err) {
>  		dev_err(&h->pdev->dev,

Wouldn't it be better to use pci_set_master(h->pdev) to enable bus
mastering?

-- 
====================================================================
Khalid Aziz                                         Unix Systems Lab
(970)898-9214                                        Hewlett-Packard
khalid.aziz@...com                                  Fort Collins, CO

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