linux-kernel - Re: [PATCH v2 0/7] mmc: meson-gx: clean up and tuning update

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Date:   Mon, 29 Apr 2019 12:44:50 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Jerome Brunet <jbrunet@...libre.com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/7] mmc: meson-gx: clean up and tuning update

On Tue, 23 Apr 2019 at 11:02, Jerome Brunet <jbrunet@...libre.com> wrote:
>
> The purpose of this series is too improve reliability of the amlogic mmc
> driver on new (g12a) and old ones (axg, gxl, gxbb, etc...)
>
> * The 3 first patches are just harmless clean ups.

Applied these first three, postponing the the rest until Martin are
happy with all of them. Thanks!

Kind regards
Uffe


> * Patch 4 makes sure HS400 can't be enabled, we still have not been able
>   to crack this modes.
> * Patch 5 removes some clock glitches when switching to DDR modes
> * Patch 6 and 7 changes the tuning method from Rx phase to signal
>   resampling. It could have been done in a single patch but the unified
>   diff was extremely ugly. The change has been split in two patches to
>   ease review.
>
> The last tuning update that went through was meant to improve the axg
> support. Since then, it was reported to break some other boards, like the
> s912 vim2.
>
> Also with the current tuning method, it was impossible to find phase
> settings which would work on all the SoCs, including the new ones.
>
> After redoing all the tests from scratch, it appeared that Rx phase made
> (strangely) almost no difference, especially on g12a and axg. However, it
> showed that it is important to have a phase shift between the Core and Tx
> clock, 180 works best.
>
> I discussed the test results with Amlogic. They suggested to use 180/0 or
> 0/180 for the Core and Tx phase. For tuning, they suggested to use
> signal resampling.
>
> So far, so good ... here the platform and modes tested:
>
> NanoPi-K2 (S905): SD UHS SDR50/DDR50, SDIO HS
> Odroid-C2 (S905): SD UHS SDR50/DDR50, eMMC DDR52/HS200 (16GB module)
> Khadas Vim (S905X): SD HS, SDIO HS, eMMC HS200
> Libretech CC (S905X): SD HS, eMMC HS200
> Khadas Vim2 (S912): SD HS, SDIO HS, eMMC HS200
> S400 (A113D): SDIO UHS SDR104, eMMC DDR52/HS200
> U200 (S905D2): SD HS, eMMC DDR52/HS200
> SEI510 (S905X2): SD HS, eMMC DDR52/HS200
>
> Changes since v1 [0]:
> * Add missing writel in patch 5 (error when switching width)
> * Change patch 3 commit description
>
> [0]: https://lkml.kernel.org/r/20190417204355.469-1-jbrunet@baylibre.com
>
> Jerome Brunet (7):
>   mmc: meson-gx: remove open coded read with timeout
>   mmc: meson-gx: ack only raised irq
>   mmc: meson-gx: correct irq flag
>   mmc: meson-gx: disable HS400
>   mmc: meson-gx: avoid clock glitch when switching to DDR modes
>   mmc: meson-gx: remove Rx phase tuning
>   mmc: meson-gx: add signal resampling tuning
>
>  drivers/mmc/host/meson-gx-mmc.c | 419 +++++++++-----------------------
>  1 file changed, 114 insertions(+), 305 deletions(-)
>
> --
> 2.20.1
>