From: Kevin Hilman <khilman@baylibre.com>
To: Neil Armstrong <narmstrong@baylibre.com>, ulf.hansson@linaro.org
Cc: Neil Armstrong <narmstrong@baylibre.com>,
baylibre-upstreaming@groups.io, linux-mmc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/3] mmc: meson-gx: add ddr-access-quirk
Date: Mon, 13 May 2019 10:47:45 -0700 [thread overview]
Message-ID: <7hd0kmckla.fsf@baylibre.com> (raw)
In-Reply-To: <20190513091548.16674-3-narmstrong@baylibre.com>
Neil Armstrong <narmstrong@baylibre.com> writes:
> On the Amlogic G12A SoC family, (only) the SDIO controller fails to access
> the data from DDR, leading to a broken controller.
>
> But each MMC controller has 1,5KiB of SRAM after the registers, that can
> be used as bounce buffer to avoid direct DDR access from the integrated
> DMAs (this SRAM may be used by the boot ROM when DDR is not yet initialized).
>
> The quirk is to disable the chained descriptor for this controller, and
> use this SRAM memory zone as buffer for the bounce buffer fallback mode.
>
> The performance hit hasn't been evaluated, but the fix has been tested
> using a WiFi AP6398S SDIO module, and the iperf3 Bandwidth measurement gave
> 55.2 Mbits/sec over a 63 Hours long test, with the SDIO ios set as High-Speed
> at 50MHz clock. It gave 170 Mbits/sec as SDR104 and 200MHz clock.
>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
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next prev parent reply other threads:[~2019-05-13 17:47 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-13 9:15 [PATCH 0/3] mmc: meson-gx: add ddr-access-quirk support Neil Armstrong
2019-05-13 9:15 ` [PATCH 1/3] dt-bindings: mmc: meson-gx: add ddr-access-quirk property Neil Armstrong
2019-05-14 17:50 ` Martin Blumenstingl
2019-05-15 12:43 ` Neil Armstrong
2019-05-15 11:37 ` Ulf Hansson
2019-05-15 12:43 ` Neil Armstrong
2019-05-13 9:15 ` [PATCH 2/3] mmc: meson-gx: add ddr-access-quirk Neil Armstrong
2019-05-13 17:47 ` Kevin Hilman [this message]
2019-05-14 17:58 ` Martin Blumenstingl
2019-05-15 12:45 ` Neil Armstrong
2019-05-15 21:18 ` Martin Blumenstingl
2019-05-16 9:09 ` Neil Armstrong
2019-05-15 11:34 ` Ulf Hansson
2019-05-15 12:51 ` Neil Armstrong
2019-05-13 9:15 ` [PATCH 3/3] arm64: dts: meson-g12a: add ddr-access-quirk property to SDIO controller Neil Armstrong
2019-05-14 17:51 ` Martin Blumenstingl
2019-05-13 9:58 ` [PATCH 0/3] mmc: meson-gx: add ddr-access-quirk support Jerome Brunet
2019-05-13 11:28 ` Jerome Brunet
2019-05-14 9:14 ` [baylibre-upstreaming] " guillaume La Roque
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