linux-kernel - Re: [PATCH v6 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer

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Date:   Wed, 12 Dec 2018 19:28:27 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     "Matwey V. Kornilov" <matwey@....msu.ru>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        matwey.kornilov@...il.com, tfiga@...omium.org,
        stern@...land.harvard.edu, ezequiel@...labora.com,
        hdegoede@...hat.com, hverkuil@...all.nl, mchehab@...nel.org,
        rostedt@...dmis.org, mingo@...hat.com, isely@...ox.com,
        bhumirks@...il.com, colin.king@...onical.com,
        kieran.bingham@...asonboard.com, keiichiw@...omium.org
Subject: Re: [PATCH v6 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer

Hi Matwey,

Thank you for the patches.

For the whole series,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

On Friday, 9 November 2018 21:03:25 EET Matwey V. Kornilov wrote:
> DMA cocherency slows the transfer down on systems without hardware coherent
> DMA. In order to demontrate this we introduce performance measurement
> facilities in patch 1 and fix the performance issue in patch 2 in order to
> obtain 3.3 times speedup.
> 
> Changes since v5:
>  * add dma_sync_single_for_device() as required by Laurent Pinchart
> 
> Changes since v4:
>  * fix fields order in trace events
>  * minor style fixes
> 
> Changes since v3:
>  * fix scripts/checkpatch.pl errors
>  * use __string to store name in trace events
> 
> Changes since v2:
>  * use dma_sync_single_for_cpu() to achive better performance
>  * remeasured performance
> 
> Changes since v1:
>  * trace_pwc_handler_exit() call moved to proper place
>  * detailed description added for commit 1
>  * additional output added to trace to track separate frames
> 
> Matwey V. Kornilov (2):
>   media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler()
>   media: usb: pwc: Don't use coherent DMA buffers for ISO transfer
> 
>  drivers/media/usb/pwc/pwc-if.c | 69 +++++++++++++++++++++++++++++++--------
>  include/trace/events/pwc.h     | 65 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 121 insertions(+), 13 deletions(-)
>  create mode 100644 include/trace/events/pwc.h

-- 
Regards,

Laurent Pinchart