From: Vinod Koul <vkoul@kernel.org>
To: Samuel Holland <samuel@sholland.org>
Cc: Chen-Yu Tsai <wens@csie.org>,
Jernej Skrabec <jernej.skrabec@gmail.com>,
Maxime Ripard <maxime@cerno.tech>,
dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev
Subject: Re: [PATCH] dmaengine: sun4i: Set the maximum segment size
Date: Tue, 5 Jul 2022 18:34:37 +0530 [thread overview]
Message-ID: <YsQ25dZ1t4bt7Stg@matsya> (raw)
In-Reply-To: <20220621031350.36187-1-samuel@sholland.org>
On 20-06-22, 22:13, Samuel Holland wrote:
> The sun4i DMA engine supports transfer sizes up to 128k for normal DMA
> and 16M for dedicated DMA, as documented in the A10 and A20 manuals.
>
> Since this is larger than the default segment size limit (64k), exposing
> the real limit reduces the number of transfers needed for a transaction.
> However, because the device can only report one segment size limit, we
> have to expose the smaller limit from normal DMA.
>
> One complication is that the driver combines pairs of periodic transfers
> to reduce programming overhead. This only works when the period size is
> at most half of the maximum transfer size. With the default 64k segment
> size limit, this was always the case, but for normal DMA it is no longer
> guaranteed. Skip the optimization if the period is too long; even
> without it, the overhead is less than before.
Applied, thanks
--
~Vinod
prev parent reply other threads:[~2022-07-05 13:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-21 3:13 [PATCH] dmaengine: sun4i: Set the maximum segment size Samuel Holland
2022-07-01 16:28 ` Vinod Koul
2022-07-01 16:46 ` Samuel Holland
2022-07-05 13:04 ` Vinod Koul [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YsQ25dZ1t4bt7Stg@matsya \
--to=vkoul@kernel.org \
--cc=dmaengine@vger.kernel.org \
--cc=jernej.skrabec@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sunxi@lists.linux.dev \
--cc=maxime@cerno.tech \
--cc=samuel@sholland.org \
--cc=wens@csie.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox