Re: [PATCH 1/2] arm: mvebu: clearfog: Fix MMC detection

Martin Rowe
2023-02-26T11:28:37Z

On Sun, 26 Feb 2023 at 11:18, Pali Rohár <pali@kernel.org> wrote:

> On Sunday 26 February 2023 01:45:16 Martin Rowe wrote:
> > On Sat, 25 Feb 2023 at 22:14, Pali Rohár <pali@kernel.org> wrote:
> > > On Saturday 25 February 2023 22:49:56 Pali Rohár wrote:
> > > > On Saturday 25 February 2023 11:42:19 Martin Rowe wrote:
> > > > > A388 Clearfog MMC is either SD Card or eMMC with different
> behaviour for
> > > > > both. Setting MMC_BROKEN_CD allows both to correctly detect MMC.
> > > > >
> > > > > Signed-off-by: Martin Rowe <martin.p.rowe@gmail.com>
> > > >
> > > > It looks like a hack but I think we do not have a better option for
> now.
> > > >
> > > > If I understand the issue correctly then card-detect pin is
> unconnected
> > > > for eMMC variant and used for checking if SD card is present for SD
> > > > variant. Unconnected pin seems to have some internal pull-up/down
> which
> > > > reports not-present state for eMMC variant. eMMC does not have any
> > > > presence signal, so card-detect pin must be ignored for eMMC.
> > > >
> > > > This looks like a chicken and egg problem and the only option to
> support
> > > > both variants is to ignore card-detect pin and always try to
> initialize
> > > > device connected to mmc controller (which may be eMMC or SD).
> > >
> > > Hm... maybe better way could be to edit armada-388-clearfog-u-boot.dtsi
> > > file and add there this? /delete-property/ cd-gpios;
> >
> > I just tried this and the device is not detected again; adding
> > "non-removable" seems to be required if changing the dts.
> >
> > > > I do not know if there is a better option for ignoring card-detect
> pin
> > > > in u-boot, so:
> >
> > I should point out that I did investigate runtime detection.
>
> But how you want to do that runtime detection? As I pointed above I
> think it is impossible do runtime detection because it is chicken and
> egg problem.
>
> You can patch fdt only after u-boot initialize mmc, so this can be used
> just for patching kernel fdt.
>

I was just trying to address your concerns about the solution looking like
a "hack". I did investigate it, and that work confirmed the issues you
expected, so that's confirmation that there isn't a better option. I think
we're saying the same thing :)

I'll look at runtime patching the kernel fdt, but it might not be as quick
a turn around as the defconfig work. If anyone looks at it before me, the
fdt memory allocation needs to be increased by 2 to fit "non-removable" in
the space left by removing the "cd-gpios".

> Patching
> > the fdt alone didn't seem to work using the hooks that were available,
> > so I started looking into how MMC was being initialised to figure out
> > if there was something changing the state of the device before it was
> > returned to BootROM. I ended up in drivers/mmc/mmc.c mmc_start_init
> > trying to figure out how we always end up with the "MMC: no card
> > present" message in the eMMC case. I was going to write some extra
> > logic around the mmc_getcd call, but realised there was already an
> > ifndef with a config that seemed like this exact use-case. Given that
> > config solved the problem it seemed like the cleanest solution.
> >
> > > > Acked-by: Pali Rohár <pali@kernel.org>
> > > >
> > > > > ---
> > > > > configs/clearfog_defconfig | 3 +--
> > > > > configs/clearfog_sata_defconfig | 8 ++++----
> > > > > 2 files changed, 5 insertions(+), 6 deletions(-)
> > > > >
> > > > > diff --git a/configs/clearfog_defconfig
> b/configs/clearfog_defconfig
> > > > > index 8cd35f9f1a..24e7c16ac7 100644
> > > > > --- a/configs/clearfog_defconfig
> > > > > +++ b/configs/clearfog_defconfig
> > > > > @@ -46,7 +46,6 @@ CONFIG_CMD_USB=y
> > > > > CONFIG_CMD_TFTPPUT=y
> > > > > CONFIG_CMD_CACHE=y
> > > > > CONFIG_CMD_TIME=y
> > > > > -CONFIG_CMD_MVEBU_BUBT=y
> > > > > CONFIG_ENV_OVERWRITE=y
> > > > > CONFIG_ENV_MIN_ENTRIES=128
> > > > > CONFIG_ARP_TIMEOUT=200
> > > > > @@ -59,7 +58,7 @@ CONFIG_DM_I2C=y
> > > > > CONFIG_SYS_I2C_MVTWSI=y
> > > > > CONFIG_I2C_EEPROM=y
> > > > > CONFIG_SPL_I2C_EEPROM=y
> > > > > -CONFIG_SUPPORT_EMMC_BOOT=y
> > > > > +CONFIG_MMC_BROKEN_CD=y
> > > > > CONFIG_MMC_SDHCI=y
> > > > > CONFIG_MMC_SDHCI_SDMA=y
> > > > > CONFIG_MMC_SDHCI_MV=y
> > > > > diff --git a/configs/clearfog_sata_defconfig
> b/configs/clearfog_sata_defconfig
> > > > > index e9b36150ea..84f900bf50 100644
> > > > > --- a/configs/clearfog_sata_defconfig
> > > > > +++ b/configs/clearfog_sata_defconfig
> > > > > @@ -6,11 +6,14 @@ CONFIG_TEXT_BASE=0x00800000
> > > > > CONFIG_SPL_LIBCOMMON_SUPPORT=y
> > > > > CONFIG_SPL_LIBGENERIC_SUPPORT=y
> > > > > CONFIG_NR_DRAM_BANKS=2
> > > > > +CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
> > > > > +CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0xff0000
> > > > > CONFIG_TARGET_CLEARFOG=y
> > > > > CONFIG_MVEBU_SPL_BOOT_DEVICE_SATA=y
> > > > > CONFIG_DEFAULT_DEVICE_TREE="armada-388-clearfog"
> > > > > CONFIG_SPL_TEXT_BASE=0x40000030
> > > > > CONFIG_SPL_SERIAL=y
> > > > > +CONFIG_SPL_STACK=0x4002c000
> > > > > CONFIG_SPL=y
> > > > > CONFIG_DEBUG_UART_BASE=0xf1012000
> > > > > CONFIG_DEBUG_UART_CLOCK=250000000
> > > > > @@ -18,8 +21,6 @@ CONFIG_SYS_LOAD_ADDR=0x800000
> > > > > CONFIG_DEBUG_UART=y
> > > > > CONFIG_AHCI=y
> > > > > CONFIG_DISTRO_DEFAULTS=y
> > > > > -CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
> > > > > -CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0xff0000
> > > > > CONFIG_BOOTDELAY=3
> > > > > CONFIG_USE_PREBOOT=y
> > > > > CONFIG_SYS_CONSOLE_INFO_QUIET=y
> > > > > @@ -31,7 +32,6 @@ CONFIG_SPL_BSS_START_ADDR=0x40023000
> > > > > CONFIG_SPL_BSS_MAX_SIZE=0x4000
> > > > > CONFIG_SPL_SYS_MALLOC_SIMPLE=y
> > > > > # CONFIG_SPL_SHARES_INIT_SP_ADDR is not set
> > > > > -CONFIG_SPL_STACK=0x4002c000
> > > > > CONFIG_SPL_I2C=y
> > > > > CONFIG_SYS_MAXARGS=32
> > > > > CONFIG_CMD_TLV_EEPROM=y
> > > > > @@ -46,7 +46,6 @@ CONFIG_CMD_USB=y
> > > > > CONFIG_CMD_TFTPPUT=y
> > > > > CONFIG_CMD_CACHE=y
> > > > > CONFIG_CMD_TIME=y
> > > > > -CONFIG_CMD_MVEBU_BUBT=y
> > > > > CONFIG_ENV_OVERWRITE=y
> > > > > CONFIG_ENV_MIN_ENTRIES=128
> > > > > CONFIG_ARP_TIMEOUT=200
> > > > > @@ -59,6 +58,7 @@ CONFIG_DM_I2C=y
> > > > > CONFIG_SYS_I2C_MVTWSI=y
> > > > > CONFIG_I2C_EEPROM=y
> > > > > CONFIG_SPL_I2C_EEPROM=y
> > > > > +CONFIG_MMC_BROKEN_CD=y
> > > > > CONFIG_SUPPORT_EMMC_BOOT=y
> > > > > CONFIG_MMC_SDHCI=y
> > > > > CONFIG_MMC_SDHCI_SDMA=y
> > > > > --
> > > > > 2.39.2
> > > > >
>