Re: [PATCH v2 2/3] mmc: k1: let the SPL read SD cards more than one block at a time

[Zixian Zeng <sycamoremoon376@gmail.com>]

On 2026/10/11 22:31, Kathpalia, Tanmay wrote:
> Hi Zixian,
> 
> Thanks for the logs.
> 
> I hit the same pattern while testing the Cadence SD6HC driver.
> Multi-block reads failed and single-block reads worked. On that board
> the host and the card were in 1.8 V mode, but the I/O supply had been
> left at 3.3 V. A short transfer got through; a longer one failed on the
> data lines.
> Both stages on K1 use the same PIO loop, so a FIFO that drains slower
> than the card delivers would show up in U-Boot proper as well. Your
> SPL/proper split fits an electrical setup difference.
> 
> The SPL failure is irq=408020. Bit 22 is the Data End Bit Error (EDEB,
> SD mode only): the controller detected 0 at the end-bit position of
> read data on DAT, or of the write CRC status. That is a bad edge on
> the data line during the transfer.
> 
> On the Banana Pi F3, aldo1 is vqmmc-supply of &sdhci0. The U-Boot
> dtsi names it vdd_1v8_mmc, and the SPL prints "vdd_1v8_mmc,
> value:1800000" before MMC2. set_vdd_mmc() in board/spacemit/k1/spl.c,
> called from board_init_f(), writes 1800000. The dts leaves aldo1 at
> 0.5 V to 3.4 V. SD High Speed (mode=2) uses 3.3 V signaling; 1.8 V is
> only after a UHS switch. mmc1_cfg is power-source 3300, and
> mmc1_uhs_cfg is the 1.8 V state. For this mode the rail should be 3.3 V.
> 
> CONFIG_SPL_MMC_IO_VOLTAGE is not set, so mmc_set_signal_voltage() is a
> stub and signal_voltage stays MMC_SIGNAL_VOLTAGE_000. aldo1 stays at
> 1.8 V. U-Boot proper has CONFIG_MMC_IO_VOLTAGE. mmc_set_initial_state()
> requests MMC_SIGNAL_VOLTAGE_330, so the driver writes 3300000 to the
> same vqmmc-supply and clears SDHCI_CTRL_VDD_180 before the transfer
> that succeeds.
> 
> CONFIG_SPL_PINCTRL is not set either. The driver calls
> pinctrl_select_state() under IS_ENABLED(CONFIG_PINCTRL), but that
> function is a stub unless CONFIG_IS_ENABLED(PINCTRL), and the return
> is ignored. SPL never applies mmc1_cfg. Proper selects "default" for
> SD_HS, which is that state.
> 
> Keeping the multi-block path, set_vdd_mmc() to 3300000, or enable
> CONFIG_SPL_MMC_IO_VOLTAGE. If the 32-block CMD18 still fails, enable
> CONFIG_SPL_PINCTRL so mmc1_cfg is applied. If either makes the read
> succeed, this is the F3 failure.
> 
> Regards,
> Tanmay

Hi Tanmay,

Your diagnosis was right - it is the I/O voltage.
Enabling CONFIG_SPL_MMC_IO_VOLTAGE makes
the multi-block read work on the Banana Pi-F3:

Based on previous commit, I patched the following changes:

diff --git a/configs/spacemit_k1_defconfig b/configs/spacemit_k1_defconfig
index 9c15d96eae2..f5c717e5965 100644
--- a/configs/spacemit_k1_defconfig
+++ b/configs/spacemit_k1_defconfig
@@ -95,6 +95,7 @@ CONFIG_MMC=y
  CONFIG_MMC_SDHCI=y
  CONFIG_MMC_SDHCI_SPACEMIT=y
  CONFIG_MMC_IO_VOLTAGE=y
+CONFIG_SPL_MMC_IO_VOLTAGE=y
  CONFIG_MMC_HS200_SUPPORT=y
  CONFIG_MMC_HS400_SUPPORT=y
  CONFIG_MMC_HS400_ES_SUPPORT=y
diff --git a/drivers/mmc/spacemit_sdhci.c b/drivers/mmc/spacemit_sdhci.c
index 23c655c6def..58374c482b3 100644
--- a/drivers/mmc/spacemit_sdhci.c
+++ b/drivers/mmc/spacemit_sdhci.c
@@ -251,6 +251,10 @@ static void spacemit_sdhci_set_voltage(struct 
sdhci_host *host)
                         bool ok;
                         int voltage_mv = to_180 ? 1800000 : 3300000;

+                       printf("sdhci: voltage signal_voltage=%u 
vqmmc=%s -> %dmV\n",
+                              mmc->signal_voltage,
+                              mmc->vqmmc_supply ? 
mmc->vqmmc_supply->name : "none",
+                              voltage_mv);
                         if (spacemit_sdhci_set_vqmmc_voltage(mmc, 
voltage_mv))
                                 return;
                         if (!IS_SD(mmc))
@@ -274,7 +278,8 @@ static void spacemit_sdhci_set_voltage(struct 
sdhci_host *host)
                         break;
                 }
                 default:
-                       /* No signal voltage switch required */
+                       printf("sdhci: voltage signal_voltage=%u -> no 
switch\n",
+                              mmc->signal_voltage);
                         return;
                 }
         }

Booting logs as follows:

U-Boot SPL 2026.10-rc5-00643-g6a99fe92389a (Oct 12 2026 - 21:13:00 +0800)
Fail to detect board:-2
vdd_core, value:900000
vdd_1v8, value:1800000
vdd_1v8_mmc, value:1800000
DDR firmware: [0xc081d880]:0xf0227179, size:0x8d98
DDR is ready
No SPI controller (-19)
Trying to boot from MMC2
sdhci: mmc@d4280000 path=PIO flags=0 caps_sdma=1 caps_adma2=1 
max_clk=204800000
sdhci: voltage signal_voltage=0 -> no switch
sdhci: voltage signal_voltage=4 vqmmc=aldo1 -> 3300000mV
sdhci: voltage signal_voltage=4 vqmmc=aldo1 -> 3300000mV
sdhci: voltage signal_voltage=4 vqmmc=aldo1 -> 3300000mV
sdhci: voltage signal_voltage=4 vqmmc=aldo1 -> 3300000mV
sdhci: voltage signal_voltage=4 vqmmc=aldo1 -> 3300000mV
mmc: multi-blk blkcnt=32 clk=50000000 mode=2 width=4 caps=300207ef 
cmd23_host=1 scr0=2358043 cmd23_card=1
sdhci: multi cmd18 arg=2 blks=32 blksz=512 mode=32 dma=0
mmc: multi-blk blkcnt=1956 clk=50000000 mode=2 width=4 caps=300207ef 
cmd23_host=1 scr0=2358043 cmd23_card=1
sdhci: multi cmd18 arg=1000 blks=1956 blksz=512 mode=32 dma=0

<debug_uart>


U-Boot 2026.10-rc5-00643-g6a99fe92389a (Oct 12 2026 - 21:13:00 +0800)

DRAM:  4 GiB
Core:  338 devices, 22 uclasses, devicetree: separate
MMC:   sdhci: mmc@d4281000 path=PIO flags=0 caps_sdma=1 caps_adma2=1 
max_clk=204800000
sdhci: mmc@d4280000 path=PIO flags=0 caps_sdma=1 caps_adma2=1 
max_clk=204800000
mmc@d4280000: 1, mmc@d4281000: 0
Loading Environment from nowhere... OK
In:    serial@d4017000
Out:   serial@d4017000
Err:   serial@d4017000
Net:   No ethernet found.
=>

With the voltage corrected, a single 1956 block PIO CMD18 loads
the whole FIT,so the controller is fine with the FIFO back pressure,
the slow SPL drain was a symptom, not the cause :-).

Without the CONFIG_SPL_MMC_IO_VOLTAGE=y change the same driver printed
"sdhci: voltage signal_voltage=0 -> no switch".
Since mmc_set_signWith the voltage corrected, a single 1956 block PIO 
CMD18 loads
the whole FIT,so the controller is fine with the FIFO back pressure,
the slow SPL drain was a symptom, not the cause :-).

Without the CONFIG_SPL_MMC_IO_VOLTAGE=y change the same driver printed
"sdhci: voltage signal_voltage=0 -> no switch".
Since mmc_set_signal_voltage() is a stub in SPL, so mmc->signal_voltage
stayed MMC_SIGNAL_VOLTAGE_000, spacemit_sdhci_set_voltage() took the
"no switch required" path, and aldo1 stayed at the initial 1800000 that
set_vdd_mmc() writes in pmic_init(). The 32 block CMD18 then failed
after ~20 of 32 blocks. Single block reads passed at 1.8 V, which is 
what hid it.

On the pinctrl side I had already run the SPL with standalone
CONFIG_SPL_PINCTRL=y, with bootph-pre-ram on &pinctrl, mmc1_cfg and
mmc1_uhs_cfg plus their pin groups. I confirmed that
pinctrl_select_state() return successfully. The multi-block read still
failed the same way with the rail at 1.8V.

Therefore, I suspect that configuring the MMC signal voltage to 1.8V
in pmic_init() may need to be modified.

Thanks for your suggestions and guidance.

Best regards,
Zixianal_voltage() is a stub in SPL, so mmc->signal_voltage
stayed MMC_SIGNAL_VOLTAGE_000, spacemit_sdhci_set_voltage() took the
"no switch required" path, and aldo1 stayed at the initial 1800000 that
set_vdd_mmc() writes in pmic_init(). The 32 block CMD18 then failed 
after ~20 of 32 blocks. Single block reads passed at 1.8 V, which is 
what hid it.

On the pinctrl side I had already run the SPL with standalone
CONFIG_SPL_PINCTRL=y, with bootph-pre-ram on &pinctrl, mmc1_cfg and
mmc1_uhs_cfg plus their pin groups. I confirmed that
pinctrl_select_state() return successfully. The multi-block read still
failed the same way with the rail at 1.8V.

Therefore, I suspect that configuring the MMC signal voltage to 1.8V
in pmic_init() may need to be modified.

Thanks for your suggestions and guidance.

Best regards,
Zixian