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
--
2.26.2
