linux-kernel - Re: [PATCH v4 07/11] dmaengine: dw: Set DMA device max segment size parameter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 29 May 2020 15:18:22 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Vinod Koul <vkoul@...nel.org>, Viresh Kumar <vireshk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 07/11] dmaengine: dw: Set DMA device max segment size
 parameter

On Fri, May 29, 2020 at 01:23:57AM +0300, Serge Semin wrote:
> Maximum block size DW DMAC configuration corresponds to the max segment
> size DMA parameter in the DMA core subsystem notation. Lets set it with a
> value specific to the probed DW DMA controller. It shall help the DMA
> clients to create size-optimized SG-list items for the controller. This in
> turn will cause less dw_desc allocations, less LLP reinitializations,
> better DMA device performance.

Yes, something like that for time being, thanks!

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: linux-mips@...r.kernel.org
> Cc: devicetree@...r.kernel.org
> 
> ---
> 
> Changelog v2:
> - This is a new patch created in place of the dropped one:
>   "dmaengine: dw: Add LLP and block size config accessors".
> 
> Changelog v3:
> - Use the block_size found for the very first channel instead of looking for
>   the maximum of maximum block sizes.
> - Don't define device-specific device_dma_parameters object, since it has
>   already been defined by the platform device core.
> ---
>  drivers/dma/dw/core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
> index 33e99d95b3d3..fb95920c429e 100644
> --- a/drivers/dma/dw/core.c
> +++ b/drivers/dma/dw/core.c
> @@ -1229,6 +1229,13 @@ int do_dma_probe(struct dw_dma_chip *chip)
>  			     BIT(DMA_MEM_TO_MEM);
>  	dw->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
>  
> +	/*
> +	 * For now there is no hardware with non uniform maximum block size
> +	 * across all of the device channels, so we set the maximum segment
> +	 * size as the block size found for the very first channel.
> +	 */
> +	dma_set_max_seg_size(dw->dma.dev, dw->chan[0].block_size);
> +
>  	err = dma_async_device_register(&dw->dma);
>  	if (err)
>  		goto err_dma_register;
> -- 
> 2.26.2
> 

-- 
With Best Regards,
Andy Shevchenko