linux-kernel - Re: [PATCH v2 1/1] mfd: intel-lpss: Try to enable Memory-Write-Invalidate

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Date:   Mon, 21 Nov 2016 13:13:16 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v2 1/1] mfd: intel-lpss: Try to enable
 Memory-Write-Invalidate

On Tue, 15 Nov 2016, Andy Shevchenko wrote:

> Enable MWI mechanism if PCI bus master supports it.
> 
> It might be potential benefit in some cases. Documentation [1] says that
> standard Memory Write might supply more current data than in the CPU modified
> cache line and "trashing a line in the cache may trash some data that is more
> current that in the memory line". This allows to avoid potential retries and
> other performance degradation issues on the bus.
> 
> [1] PCI System Architecture, 4th edition, ISBN: 0-201-30974-2, pp.117-119.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> In v2:
> - extend commit message
>  drivers/mfd/intel-lpss-pci.c | 1 +
>  1 file changed, 1 insertion(+)

Applied, thanks.

> diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c
> index 50e78db..4756153 100644
> --- a/drivers/mfd/intel-lpss-pci.c
> +++ b/drivers/mfd/intel-lpss-pci.c
> @@ -41,6 +41,7 @@ static int intel_lpss_pci_probe(struct pci_dev *pdev,
>  
>  	/* Probably it is enough to set this for iDMA capable devices only */
>  	pci_set_master(pdev);
> +	pci_try_set_mwi(pdev);
>  
>  	ret = intel_lpss_probe(&pdev->dev, info);
>  	if (ret)

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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