Date:   Fri, 21 Jan 2022 08:43:22 -0500
From:   "Gabriel L. Somlo" <gsomlo@...il.com>
To:     Gabriel Somlo <gsomlo@...il.com>
Cc:     linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        devicetree@...r.kernel.org, ulf.hansson@...aro.org,
        linux-mmc@...r.kernel.org, kgugala@...micro.com,
        mholenko@...micro.com, krakoczy@...micro.com,
        mdudek@...ernships.antmicro.com, paulus@...abs.org, joel@....id.au,
        shorne@...il.com, geert@...ux-m68k.org,
        david.abdurachmanov@...ive.com, florent@...oy-digital.fr,
        rdunlap@...radead.org, andy.shevchenko@...il.com, hdanton@...a.com
Subject: Re: [PATCH v14 0/3] mmc: Add LiteSDCard mmc driver

On Thu, Jan 13, 2022 at 12:02:57PM -0500, Gabriel Somlo wrote:
> Add support for the LiteX SD-Card device, LiteSDCard.
> 
> LiteSDCard is a simple SD-Card interface available as part of the LiteX
> environment, used with various RISC-V and other FPGA based SoCs.
> 
> New in v14:
> Documentation/devicetree/bindings/mmc/litex,mmc.yaml:
>   - add missing `vmmc-supply = ...` property to example section
> 
> >New in v13:
> >Documentation/devicetree/bindings/mmc/litex,mmc.yaml:
> >  - add `vmmc-supply` requirement
> >drivers/mmc/host/Kconfig:
> >  - add dependency on REGULATOR, REGULATOR_FIXED_VOLTAGE
> >drivers/mmc/host/litex_mmc.c:
> >  - use `mmc_regulator_get_supply()`, with fallback to hardcoded 3.3V


Ping?


> >>New in v12:
> >>drivers/mmc/host/Kconfig:
> >>  - add dependency on HAVE_CLK for litex_mmc driver
> >>  - (re)add "If unsure, say N" to the litex_mmc driver help message
> >>drivers/mmc/host/litex_mmc.c:
> >>  - prints message using dev_info() before returning success from probe()
> >>
> >>>New in v11:
> >>>  - picked up r/b from Andy
> >>>drivers/mmc/host/litex_mmc.c:
> >>>  - defensive coding of litex_mmc_interrupt() return logic
> >>>  - remove `dev` member of `struct litex_mmc_host`, only used during probe
> >>>
> >>>>New in v10:
> >>>>drivers/mmc/host/litex_mmc.c:
> >>>>  - group `linux/mmc/*` includes by themselves
> >>>>  - clean-up of `return` style (multiple locations throughout source)
> >>>>  - create `mmc_free_host()` wrapper for use with
> >>>>    `devm_add_action_or_reset()`
> >>>>  - use GFP_KERNEL with `dmam_alloc_coherent()`
> >>>>
> >>>>>New in v9:
> >>>>>drivers/mmc/host/Kconfig:
> >>>>>  - fix OF dependency
> >>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>  - remove `linux/of.h` include, no longer needed since dropping
> >>>>>    `of_match_ptr()`
> >>>>>  - add `linux/mod_devicetable.h` include
> >>>>>  - use devm_action_or_reset() to devm-ify mmc_alloc_host(), and obviate
> >>>>>    the need to call mmc_free_host() explicitly during either probe()
> >>>>>    error path or during remove()
> >>>>>
> >>>>>>New in v8:
> >>>>>>commit blurbs:
> >>>>>>  - cosmetic editing of descriptions
> >>>>>>  - removed `Cc:` lines
> >>>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>>  - fix file header comment (for real, this time)
> >>>>>>  - add explicit `bits.h` include
> >>>>>>  - remove `of_match_ptr()` wrapper from around .of_match_table argument
> >>>>>>  - fix devm ordering issues: use `devm_request_irq()`, which precludes
> >>>>>>    the need to call `free_irq()` on `probe()` error path or from `remove()`
> >>>>>>
> >>>>>>>New in v7:
> >>>>>>>
> >>>>>>>drivers/mmc/host/Kconfig:
> >>>>>>>  - added module name in LiteSDCard Kconfig entry
> >>>>>>>
> >>>>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>>>  - fixed comment formatting, ordering, and capitalization throughout
> >>>>>>>    the entire file
> >>>>>>>  - sorted header #include statements
> >>>>>>>  - removed redundant parantheses in readx_poll_timeout() condition
> >>>>>>>  - explicit handling of readx_poll_timeout() timeout scenarios
> >>>>>>>  - dev_err() used in litex_mmc_sdcard_wait_done()
> >>>>>>>  - use memcpy_fromio() to grab command response
> >>>>>>>  - no need to apply 0xffff mask to a 32-bit value right-shifted by 16
> >>>>>>>    (host->resp[3])
> >>>>>>>  - use clamp() instead of min(max(...)...)
> >>>>>>>  - reworked platform_get_irq_optional() error handling logic
> >>>>>>>  - no need to explicitly zero host->irq, kzalloc() does that already
> >>>>>>>  - added missing free_irq() in litex_mmc_probe() error path
> >>>>>>>  - reordered calls inside litex_mmc_remove() (calling mmc_free_host()
> >>>>>>>    before free_irq()
> >>>>>>>
> >>>>>>>>New in v6:
> >>>>>>>>
> >>>>>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>>>>  - fix handling of deferred probe vs. platform_get_irq_optional()
> >>>>>>>>  - don't #ifdef dma_set_mask_and_coherent(), since it automatically
> >>>>>>>>    does the right thing on both 32- and 64-bit DMA capable arches
> >>>>>>>>  - remove MMC_CAP2_FULL_PWR_CYCLE, add MMC_CAP2_NO_MMC to list of
> >>>>>>>>    hardcoded capabilities during litex_mmc_probe()
> >>>>>>>>  - hardcode mmc->ocr_avail to the full 2.7-3.6V range allowed by the
> >>>>>>>>    SDCard spec (the LiteSDCard device doesn't accept software
> >>>>>>>>    configuration)
> >>>>>>>>
> >>>>>>>>>New in v5:
> >>>>>>>>>
> >>>>>>>>>MAINTAINERS:
> >>>>>>>>>
> >>>>>>>>>  - picked up a/b Mateusz
> >>>>>>>>>
> >>>>>>>>>Doc/dt/bindings/mmc/litex,mmc.yaml:
> >>>>>>>>>
> >>>>>>>>>  - picked up r/b Rob, Joel
> >>>>>>>>>
> >>>>>>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>>>>>
> >>>>>>>>>  - shorten #define constant names (cosmetic, make them less unwieldy)
> >>>>>>>>>  - picked up r/b Joel
> >>>>>>>>>
> >>>>>>>>>>New in v4:
> >>>>>>>>>>
> >>>>>>>>>>Doc/dt/bindings/mmc/litex,mmc.yaml:
> >>>>>>>>>>
> >>>>>>>>>>  - fixed `dt_binding_check` errors uncovered by Rob's script
> >>>>>>>>>>
> >>>>>>>>>>drivers/mmc/host/litex_mmc.c:
> >>>>>>>>>>
> >>>>>>>>>>  - struct litex_mmc_host fields re-ordered so that `pahole` reports
> >>>>>>>>>>    no holes in either 32- or 64-bit builds
> >>>>>>>>>>  - litex_mmc_set_bus_width() now encapsulates check for
> >>>>>>>>>>    host->is_bus_width_set
> >>>>>>>>>>  - litex_mmc_request() - factor out dma data setup into separate
> >>>>>>>>>>    helper function: litex_mmc_do_dma()
> >>>>>>>>>>
> >>>>>>>>>>>New in v3:
> >>>>>>>>>>>
> >>>>>>>>>>>  MAINTAINERS:
> >>>>>>>>>>>
> >>>>>>>>>>>  - picked up acked-by Joel
> >>>>>>>>>>>  - added listing for liteeth driver
> >>>>>>>>>>>  - added Joel as additional co-maintainer (thanks!)
> >>>>>>>>>>>
> >>>>>>>>>>>  Doc/dt/bindings/mmc/litex,mmc.yaml:
> >>>>>>>>>>>
> >>>>>>>>>>>  - picked up r/b Geert Uytterhoeven <geert@...ux-m68k.org> in DT
> >>>>>>>>>>>    bindings document (please let me know if that was premature, and
> >>>>>>>>>>>    happy to take further review if needed :)
> >>>>>>>>>>>  - add dedicated DT property for source clock frequency
> >>>>>>>>>>>
> >>>>>>>>>>>  drivers/mmc/host/litex_mmc.c:
> >>>>>>>>>>>
> >>>>>>>>>>>  - fixed function signature (no line split), and naming (litex_mmc_*)
> >>>>>>>>>>>  - more informative MODULE_AUTHOR() entries
> >>>>>>>>>>>    - also added matching "Copyright" entries in file header
> >>>>>>>>>>>  - fixed description in Kconfig
> >>>>>>>>>>>  - fixed DT documentation
> >>>>>>>>>>>  - removed magic constants
> >>>>>>>>>>>  - removed litex_map_status(), have sdcard_wait_done() return *real*
> >>>>>>>>>>>    error codes directly instead.
> >>>>>>>>>>>  - streamlined litex_mmc_reponse_len()
> >>>>>>>>>>>  - call litex_mmc_set_bus_width() only once, and ensure it returns
> >>>>>>>>>>>    correct error code(s)
> >>>>>>>>>>>  - use readx_poll_timeout() -- more concise -- instead of
> >>>>>>>>>>>    read_poll_timeout()
> >>>>>>>>>>>  - use dev_err() in litex_mmc_send_cmd() (instead of pr_err())
> >>>>>>>>>>>  - litex_mmc_setclk() will update host->clock before returning
> >>>>>>>>>>>  - separate irq initialization into its own function,
> >>>>>>>>>>>    litex_mmc_irq_init()
> >>>>>>>>>>>  - document rationale for f_min, f_max
> >>>>>>>>>>>  - use dmam_alloc_coherent(), which simplifies cleanup significantly
> >>>>>>>>>>>  - large `if (data) { ... }` block in litex_mmc_request() left as-is,
> >>>>>>>>>>>    there are too many variables shared with the rest of the parent
> >>>>>>>>>>>    function body to easily separate (e.g., `len`, `transfer`, `direct`).
> >>>>>>>>>>>    If this is indeed a blocker, I can take another shot at refactoring
> >>>>>>>>>>>    it in a future revision!
> >>>>>>>>>>>  - bump dma_set_mask_and_coherent() to 64-bits on suitable
> >>>>>>>>>>>    architectures
> >>>>>>>>>>>  - clock source picked up from dedicated DT clock reference property
> >>>>>>>>>>>  - remove gpio card-detect logic (needs testing and a dt binding
> >>>>>>>>>>>    example before being eligible for upstream inclusion)
> >>>>>>>>>>>
> >>>>>>>>>>>> New in v2:
> >>>>>>>>>>>>   - reword info message in litex_set_clk()
> >>>>>>>>>>>>   - streamline code in litex_map_status()
> >>>>>>>>>>>>   - fix typos in Kconfig (thanks Randy Dunlap <rdunlap@...radead.org>)
> >>>>>>>>>>>>   - improvements suggested by Stafford Horne <shorne@...il.com>
> >>>>>>>>>>>>     - allow COMPILE_TEST in Kconfig
> >>>>>>>>>>>>     - use read_poll_timeout() when waiting for cmd/data/DMA
> >>>>>>>>>>>>       xfer completion
> >>>>>>>>>>>>   - include interrupt.h (thanks kernel test robot <lkp@...el.com>)
> 
> Gabriel Somlo (3):
>   MAINTAINERS: co-maintain LiteX platform
>   dt-bindings: mmc: Add bindings for LiteSDCard
>   mmc: Add driver for LiteX's LiteSDCard interface
> 
>  .../devicetree/bindings/mmc/litex,mmc.yaml    |  78 +++
>  MAINTAINERS                                   |   9 +-
>  drivers/mmc/host/Kconfig                      |  13 +
>  drivers/mmc/host/Makefile                     |   1 +
>  drivers/mmc/host/litex_mmc.c                  | 661 ++++++++++++++++++
>  5 files changed, 760 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/mmc/litex,mmc.yaml
>  create mode 100644 drivers/mmc/host/litex_mmc.c
> 
> -- 
> 2.31.1
> 

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