linux-kernel - [PATCH v2 0/2] soundwire: Remove redundant zeroing of page registers

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Message-ID: <20230123164949.245898-1-rf@opensource.cirrus.com>
Date:   Mon, 23 Jan 2023 16:49:47 +0000
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <vkoul@...nel.org>, <yung-chuan.liao@...ux.intel.com>,
        <pierre-louis.bossart@...ux.intel.com>, <sanyog.r.kale@...el.com>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH v2 0/2] soundwire: Remove redundant zeroing of page registers

Writing zero to the page registers after each message transaction can add
up to a lot of overhead for codecs that need to transfer large amount of
data - for example a firmware download.

There's no spec reason I can see for this zeroing. The page registers are
only used for a paged address. The bus code uses a non-paged address for
registers in page 0. It always writes the page registers at the start of
a paged transaction.

If this zeroing was a workaround for anything, let me know and I will
re-implement the zeroing as a quirk that can be enabled only when it is
necessary.

Changes since v1:
- Reworded the commit message to patch #1:
  - say that this is for devices that support paging
  - mention bit 15 as the paging flag
  - split a long sentence into two sentences.

No code changes.

Richard Fitzgerald (2):
  soundwire: bus: Don't zero page registers after every transaction
  soundwire: bus: Remove unused reset_page_addr() callback

 drivers/soundwire/bus.c             | 23 -----------------------
 drivers/soundwire/cadence_master.c  | 14 --------------
 drivers/soundwire/cadence_master.h  |  3 ---
 drivers/soundwire/intel_auxdevice.c |  1 -
 include/linux/soundwire/sdw.h       |  3 ---
 5 files changed, 44 deletions(-)

-- 
2.30.2