From: Dmitry Osipenko <digetx@gmail.com>
To: Sowjanya Komatineni <skomatineni@nvidia.com>,
thierry.reding@gmail.com, jonathanh@nvidia.com,
mkarthik@nvidia.com, smohammed@nvidia.com, talho@nvidia.com
Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-i2c@vger.kernel.org
Subject: Re: [PATCH V3 3/3] i2c: tegra: Add DMA Support
Date: Sun, 27 Jan 2019 00:24:36 +0300 [thread overview]
Message-ID: <5973707c-555f-a27c-2ff3-e867d4b2cde7@gmail.com> (raw)
In-Reply-To: <1548475073-12408-3-git-send-email-skomatineni@nvidia.com>
26.01.2019 6:57, Sowjanya Komatineni пишет:
> This patch adds DMA support for Tegra I2C.
>
> Tegra I2C TX and RX FIFO depth is 8 words. PIO mode is used for
> transfer size of the max FIFO depth and DMA mode is used for
> transfer size higher than max FIFO depth to save CPU overhead.
>
> PIO mode needs full intervention of CPU to fill or empty FIFO's
> and also need to service multiple data requests interrupt for the
> same transaction adding overhead on CPU for large transfers.
>
> DMA mode is helpful for Large transfers during downloading or
> uploading FW over I2C to some external devices.
>
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>
> ---
Seems there are good news, APB DMA could access IRAM. Quote from TRM: "The source may be DRAM or IRAM, and the destination location could be devices placed on APB Bus; or vice versa". Hence it shall be much more efficient to use IRAM for the DMA buffer, please consider that variant.
next prev parent reply other threads:[~2019-01-26 21:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-26 3:57 [PATCH V3 1/3] i2c: tegra: Sort all the include headers alphabetically Sowjanya Komatineni
2019-01-26 3:57 ` [PATCH V3 2/3] i2c: tegra: Update transfer timeout Sowjanya Komatineni
2019-01-26 18:02 ` Dmitry Osipenko
2019-01-28 18:28 ` Sowjanya Komatineni
2019-01-28 22:08 ` Dmitry Osipenko
2019-01-28 22:15 ` Sowjanya Komatineni
2019-01-28 22:27 ` Dmitry Osipenko
2019-01-28 22:31 ` Sowjanya Komatineni
2019-01-29 10:15 ` Thierry Reding
2019-01-29 10:16 ` Thierry Reding
2019-01-29 11:21 ` Dmitry Osipenko
2019-01-26 3:57 ` [PATCH V3 3/3] i2c: tegra: Add DMA Support Sowjanya Komatineni
2019-01-26 17:11 ` Dmitry Osipenko
2019-01-26 18:16 ` Dmitry Osipenko
2019-01-26 17:29 ` Dmitry Osipenko
2019-01-26 20:42 ` Dmitry Osipenko
2019-01-26 21:24 ` Dmitry Osipenko [this message]
2019-01-28 23:47 ` Sowjanya Komatineni
2019-01-29 2:02 ` Sowjanya Komatineni
2019-01-29 3:11 ` Dmitry Osipenko
2019-01-26 17:29 ` [PATCH V3 1/3] i2c: tegra: Sort all the include headers alphabetically Dmitry Osipenko
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