Re: [PATCH v7 0/2] Amlogic 32-bit Meson SoC SDHC MMC controller driver

[Ulf Hansson]

On Tue, 12 May 2020 at 22:42, Martin Blumenstingl
<martin.blumenstingl@xxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> this is the patchset for a driver for the Amlogic "SDHC" MMC controller
> found on Meson6, Meson8, Meson8b and Meson8m2 SoCs.
>
> The public S805 (Meson8b) datasheet has some documentation starting on
> page 74: [0]
>
> It's performance is still not as good as the driver from Amlogic's 3.10
> kernel, but it does not corrupt data anymore (as RFC v1 did).
>
> Special thanks to the people who supported me off-list - you are
> amazing and deserve to be mentioned here:
> - Xin Yin who helped me fix two more write corruption problems. I am
>   hoping that he will reply with Reviewed-by, Tested-by and Bug-fixed-by
> - Jianxin Pan for sharing some of the internal workings of this MMC
>   controller with me
> - Wei Wang for spotting the initial write corruption problem and helping
>   test this driver on his board. I have his permission to add his
>   Tested-by (off-list, he's Cc'ed so if there's any problem he can speak
>   up)
>
>
> Changes since v6 at [6]:
> - both patches: dropped the clock #include from the dt-bindings as well
>   as #clock-cells = <1> and the self-referencing clock inputs. Instead
>   the driver will not be registering a clock provider anymore. The
>   clock references are obtained using "clk_hw.clk" (thus not going
>   through the dt-bindings anymore) as suggested in [7] until a better
>   solution is implemented. A TODO comment is also in place so it's
>   easier to find this temporary workaround when the new helper exists.
> - dropped Rob's Reviewed-by because I modified the dt-bindings. schema
>   validation still passes on my build machine.
> - patch #2: dropped MMC_CAP_ERASE due to the following patch which is
>   queued in mmc's -next: "mmc: host: Drop redundant MMC_CAP_ERASE"
> - patch #2: fill all clk_{mux,divider,gate,hw} values in
>   meson_mx_sdhc_register_clkc instead of using loops and two separate
>   structs to make the code easier to read. Thanks to Jerome for the
>   suggestion.
> - I decided to keep all the Tested-by's because testing was smooth
>   for me and none of the clock calculation formulas has changed (only
>   the API how to obtain the clocks).
>
> Changes since v5 at [5] (thanks to Ulf and Jerome for the feedback):
> - changed copyright year to 2020
> - move register #defines to a separate header file
> - drop unused include linux/clk-provider.h from meson-mx-sdhc.c
> - used #defines for regmap_read_poll_timeout timeout/sleep values
> - set MMC_CAP_WAIT_WHILE_BUSY
> - move the clock controller code to mmc/host/meson-mx-sdhc-clkc.c and
>   don't register a separate platform_device for it. This also means
>   that the driver switched from clk_regmap to the standard
>   clk_{divider,gate,mux}_ops
> - dropped ".index = -1" for clk_parent_data with .fw_name
> - use CLK_SET_RATE_PARENT on all leaf clocks and drop
>   CLK_SET_RATE_GATE
> - switch from parent_data.name to parent_hws
> - use fallthrough; instead of fallthrough comment
> - added Anand's Tested-by - thank you!
> - I decided to keep all Tested-by and Reviewed-by because they were
>   only for the MMC controller part and I have barely touched that with
>   this update.
> - Ulf asked if the timeout can be shortened. I believe it can but I
>   have no documentation for it. Thus I need a test-case to see if my
>   assumptions are correct - thus I have not addressed this in v6 yet
>
> Changes since v4 at [4]:
> - move the four clkin clock inputs to the start of the clock-names list
>   as suggested by Rob, affects patch #1
> - fixed #include statement in dt-bindings example in patch #1
>
> Changes since v3 at [3]:
> - split the clock bits into a separate clock controller driver because
>   of two reasons: 1) it keeps the MMC controller driver mostly clean of
>   the clock bits 2) the pure clock controller can use
>   devm_clk_hw_register() (instead of devm_clk_register(), which is
>   deprecated) and the MMC controller can act as a pure clock consumer.
>   This also affects the dt-bindings which is why I dropped Rob's
>   Reviewed-by. Thanks to Ulf for the suggestions
>
> Changes since v2 at [2]:
> - rebased on top of v5.5-rc1
> - added Rob's and Xin Yin's Reviewed-by and Tested-by (thank you!)
> - (note: Kevin had v2 of this series in -next for a few days so the
>    build test robots could play with it. I haven't received any negative
>    feedback in that time)
>
> Changes since RFC v1 at [1]:
> - don't set MESON_SDHC_MISC_MANUAL_STOP to fix one of three write
>   corruption problems. the out-of-tree 3.10 "reference" driver doesn't
>   set it either
> - check against data->flags instead of cmd->flags when testing for
>   MMC_DATA_WRITE as spotted by Xin Yin (many thanks!). This fixes
>   another write corruption problem
> - clear the FIFOs after successfully transferring data as suggested by
>   Xin Yin (many thanks!). This is what the 3.10 driver did and fixes yet
>   another write corruption problem
> - integrate the clock suggestions from Jianxin Pan so the driver is now
>   able to set up the clocks correctly for all known cases. documentation
>   is also added to the patch description. Thank you Jianxin for the
>   help!
> - set the correct max_busy_timeout as suggested by Jianxin Pan (thanks!)
> - convert the dt-bindings to .yaml (which is why I didn't add Rob's
>   Reviewed-by)
> - switch to struct clk_parent_data as part of newer common clock
>   framework APIs to simplify the clock setup
> - dropped CMD23 support because it seems to hurt read and write
>   performance by 10-20% in my tests. it's not clear why, but for now we
>   can live without this.
> - use devm_platform_ioremap_resource instead of open-coding it
>
>
> [0] https://dn.odroid.com/S805/Datasheet/S805_Datasheet%20V0.8%2020150126.pdf
> [1] https://patchwork.kernel.org/cover/11035505/
> [2] http://lists.infradead.org/pipermail/linux-amlogic/2019-November/014576.html
> [3] https://patchwork.kernel.org/cover/11283179/
> [4] https://patchwork.kernel.org/cover/11329017/
> [5] https://patchwork.kernel.org/cover/11463341/
> [6] https://patchwork.kernel.org/cover/11515603/
> [7] https://lore.kernel.org/linux-clk/158870581453.26370.15255632521260524214@xxxxxxxxxxxxxxxxxxxxxxxxxx/
>
>
> Martin Blumenstingl (2):
>   dt-bindings: mmc: Document the Amlogic Meson SDHC MMC host controller
>   mmc: host: meson-mx-sdhc: new driver for the Amlogic Meson SDHC host
>
>  .../bindings/mmc/amlogic,meson-mx-sdhc.yaml   |  68 ++
>  drivers/mmc/host/Kconfig                      |  14 +
>  drivers/mmc/host/Makefile                     |   1 +
>  drivers/mmc/host/meson-mx-sdhc-clkc.c         | 158 +++
>  drivers/mmc/host/meson-mx-sdhc.c              | 907 ++++++++++++++++++
>  drivers/mmc/host/meson-mx-sdhc.h              | 141 +++
>  6 files changed, 1289 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mmc/amlogic,meson-mx-sdhc.yaml
>  create mode 100644 drivers/mmc/host/meson-mx-sdhc-clkc.c
>  create mode 100644 drivers/mmc/host/meson-mx-sdhc.c
>  create mode 100644 drivers/mmc/host/meson-mx-sdhc.h
>

Applied for next, thanks!

Kind regards
Uffe