[...]

quoted

quoted

+
+static int __xenon_emmc_delay_adj_test(struct mmc_card *card)
+{
+       int err;
+       u8 *ext_csd = NULL;
+
+       err = mmc_get_ext_csd(card, &ext_csd);
+       kfree(ext_csd);

Why do you read the ext csd here?

   I would like to simply introduce the PHY setting of our SDHC.
   The target of the PHY setting is to achieve a perfect sampling
   point for transfers, during card initialization.

Okay, so the phy is involved when running the tuning sequence.

   For HS200/HS400/SDR104 whose SDCLK is more than 50MHz, SDHC HW
   will search for this sampling point with DLL's help.

Apologize for my ignorance, but what is a "DLL" in this case?

   For other speed mode whose SDLCK is less than or equals to 50MHz,
   SW has to scan the PHY delay line to find out this perfect sampling
   point. Our driver sends a command to verify a sampling point
   in current environment.

Ahh, okay! I guess the important part here is to not only send a
command, but also to make sure data becomes transferred on the DAT
lines, as to confirm your tuning sequence!?

In cases of HS200/HS400/SDR104 you should be able to use the
mmc_send_tuning() API, don't you think?

For the other cases (lower speed modes) which cards doesn't support
the tuning command, perhaps you can just assume the PHY scan succeeded
and then allow to core to continue with the card initialization
sequence? Or do you foresee any issues with that? My point is that, if
it will fail - it will fail anyway.

   As result, our SDHC driver has to implement the functionality to
   send commands and check the results, in host layer.
   If directly calling mmc_wait_for_cmd() is improper, could you please
   give us some suggestions?

   For eMMC, CMD8 is used to test current sampling point set in PHY.

Try to use mmc_send_tuning().

quoted

quoted

+
+       return err;
+}
+
+static int __xenon_sdio_delay_adj_test(struct mmc_card *card)
+{
+       struct mmc_command cmd = {0};
+       int err;
+
+       cmd.opcode = SD_IO_RW_DIRECT;
+       cmd.flags = MMC_RSP_R5 | MMC_CMD_AC;
+
+       err = mmc_wait_for_cmd(card->host, &cmd, 0);
+       if (err)
+               return err;
+
+       if (cmd.resp[0] & R5_ERROR)
+               return -EIO;
+       if (cmd.resp[0] & R5_FUNCTION_NUMBER)
+               return -EINVAL;
+       if (cmd.resp[0] & R5_OUT_OF_RANGE)
+               return -ERANGE;
+       return 0;

No thanks! MMC/SD/SDIO protocol code belongs in the core.

   For SDIO, SD_IO_RW_DIRECT command is sent to test current sampling point
   in PHY.
   Please help provide some suggestion to implement the command transfer.

Again, I think mmc_send_tuning() should be possible for you to use.

[...]

quoted

quoted

+       if (mmc->card)
+               card = mmc->card;
+       else
+               /*
+                * Only valid during initialization
+                * before mmc->card is set
+                */
+               card = priv->card_candidate;
+       if (unlikely(!card)) {
+               dev_warn(mmc_dev(mmc), "card is not present\n");
+               return -EINVAL;
+       }

That your host need to hold a copy of the card pointer, tells me that
something is not really correct.

I might be wrong, if this turns out to be a special case, but I doubt
it. Although, if it *is* a special such case, we shall most likely try
to extend the the mmc core layer instead of adding all these hacks in
your host driver.

    This card pointer copies the temporary structure mmc_card
    used in mmc_init_card(), mmc_sd_init_card() and mmc_sdio_init_card().
    Since we call mmc_wait_for_cmd() to send test commands, we need a copy
    of that temporary mmc_card here in our host driver.

I see, thanks for clarifying.

    During PHY setting in card initialization, mmc_host->card is not updated
    yet with that temporary mmc_card. Thus we are not able to directly use
    mmc_host->card. Instead, this card pointer is introduced to enable
    mmc_wait_for_cmd().

    If we can improve our host driver to send test commands without mmc_card,
    this card pointer can be removed.
    Could you please share your opinion please?

The mmc_send_tuning() API takes the mmc_host as parameter. If you
convert to that, perhaps you would be able to remove the need to hold
the card pointer.

BTW, the reason why mmc_send_tuning() doesn't take the card as a
parameter, is exactly those you just described above.

[...]

Kind regards
Uffe
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