Re: [RFC PATCH] mmc: dw_mmc: remove redundant num_slots check

Jaehoon Chung
2016-01-22T02:46:54Z

Hi, Shawn.

On 01/21/2016 04:52 PM, Shawn Lin wrote:
> num_slots comes from pdata if existing, otherwise from
> dw_mci_parse_dt which make it at least one slot. If
> num_slots is less than 1 for the existing pdata case,
> current code return -ENODEV. But dw_mci_probe seems to
> treat this a optional case as it will call SDMMC_GET_SLOT_NUM
> if no slot assigned.

Well, we need to consider more thing..
Host can get the number of slot from SDMMC_GET_SLOT_NUM().
But i think this way also has the problem.

num_slot isn't defined anywhere, and num_slot should be set to value of SDMMC_GET_SLOT_NUM.
If that value is higher than 1, it should be blocking..(I didn't test all cases..)

Even though this patch is not correct, i could check the problem relevant to num_slot, because of this patch. :)

my suggestion is if pdata->num_slot is not defined anywhere, just set to 1 by default.
not take from SDMMC_GET_SLOT_NUM.

if (host->pdata->nums_slots < 1 ||
host->pdata->nums_slots > SDMMC_GET_SLOT_NUM())

This is correct condition. num_slots can't be higher than number of supported slots.
how about?

Best Regards,
Jaehoon Chung

>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>
> ---
>
> drivers/mmc/host/dw_mmc.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 7128351..a116ec6 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2949,12 +2949,6 @@ int dw_mci_probe(struct dw_mci *host)
> }
> }
>
> - if (host->pdata->num_slots < 1) {
> - dev_err(host->dev,
> - "Platform data must supply num_slots.\n");
> - return -ENODEV;
> - }
> -
> host->biu_clk = devm_clk_get(host->dev, "biu");
> if (IS_ERR(host->biu_clk)) {
> dev_dbg(host->dev, "biu clock not available\n");
>