Re: [RFC PATCH 0/2] mmc: k1: do not require max-frequency in the device tree

[Yixun Lan <dlan@kernel.org>]

Hi Hung-Chun,

On 16:44 Tue 13 Oct     , Hung-Chun Tseng wrote:
> The K1 SDHCI driver sets the io clock to cfg.f_max, which is only
> filled in from a "max-frequency" property, so each K1 board carries
> max-frequency = <204800000> for the SD and eMMC nodes in its
> -u-boot.dtsi. E Shattow pointed out that this property is unlikely to
> be accepted in the upstream device tree and looks like a driver issue
> [1]. The Linux driver indeed does not need it: it reports the current
> io clock rate as the maximum.
> 
> Patch 1 makes the U-Boot driver do the same when max-frequency is
> absent. Patch 2 drops the property from the BPI-F3 and MusePi Pro
> overlays.
> 
> This is an RFC because I could only build-test it: spacemit_k1_defconfig
> builds (SPL and u-boot.itb), and the resulting BPI-F3 and MusePi Pro
> DTBs no longer carry max-frequency on the MMC nodes. I have not run it
> on hardware. The open question is what rate the io clock runs at when
> SPL and U-Boot probe the controllers: if the BootROM or SPL leaves it
> well below 204.8 MHz, SD and eMMC will still work but run slower, and
> the driver may need a default rate instead of the current one. A test
> on a BPI-F3 or MusePi Pro, or a pointer to the expected clock setup,
> would be very welcome.
> 
> [1] https://lore.kernel.org/u-boot/5d323a11-da4e-4071-bdeb-ab5c03e8f85e@freeshell.de/
> 
Please do not start a new thread, as there is already one discussion, see
https://lore.kernel.org/all/20261005T135220-0400.mmc-v2-0001.DaveWK225@protonmail.com/

> Hung-Chun Tseng (2):
>   mmc: k1: use the io clock rate when max-frequency is absent
>   riscv: dts: k1: drop max-frequency from the SD and eMMC nodes
> 
>  arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi |  2 --
>  arch/riscv/dts/k1-musepi-pro-u-boot.dtsi  |  2 --
>  drivers/mmc/spacemit_sdhci.c              | 24 +++++++++++++++++++----
>  3 files changed, 20 insertions(+), 8 deletions(-)
> 
> -- 
> 2.43.0
> 

-- 
Yixun Lan (dlan)