Re: [PATCH v2] mci: add new MCI_BROKEN_CD option for testing

[Sascha Hauer <sha@pengutronix.de>]

On Mon, Jul 25, 2022 at 01:58:56PM +0200, Ahmad Fatoum wrote:
> In remote labs co-located with other hardware, we've observed card
> detect levers of different boards to sporadically fail to detect
> the card, e.g. because the cable on the usbsdmux was yanked around
> by accident. When this happens, barebox usually boots up normally as
> the card detect is ignored and then Linux waits indefinitely for
> the card-detect to turn active. Add a new config option that can be
> enabled to avoid these issues altogether.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> v1 -> v2:
>   - use early exit instead of if-else
>   - don't fail mci_card_probe if of_register_fixup fails
> ---
>  drivers/mci/Kconfig    | 15 +++++++++++++++
>  drivers/mci/mci-core.c | 36 ++++++++++++++++++++++++++++++++----
>  2 files changed, 47 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mci/Kconfig b/drivers/mci/Kconfig
> index 21d53c0c3f0b..651e59259790 100644
> --- a/drivers/mci/Kconfig
> +++ b/drivers/mci/Kconfig
> @@ -56,6 +56,21 @@ config MCI_MMC_GPP_PARTITIONS
>  	  Note: by default, 'MMC' devices have no 'general purpose partitions',
>  	  it requires a special one-time configuration step to enable them.
>  
> +config MCI_BROKEN_CD
> +	bool "ignore card-detect pin on boot and in OS"
> +	help
> +	  Say 'y' here to have barebox unconditionally ignore the
> +	  card-detect pin for its own operation and manipulate the
> +	  kernel DT, so all detected MCI cards are polled instead
> +	  of expecting the card detect lever to behave correctly.
> +	  If you need more fine grained control use of_property
> +	  in an init script:
> +
> +	    of_property -fd mmc0 cd-gpios
> +	    of_property -fs mmc0 broken-cd
> +
> +	  If unsure, say 'n' here.
> +
>  comment "--- MCI host drivers ---"
>  
>  config MCI_DW
> diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> index 82e2f82f5377..4db2253c3a80 100644
> --- a/drivers/mci/mci-core.c
> +++ b/drivers/mci/mci-core.c
> @@ -1727,6 +1727,27 @@ static int mci_register_partition(struct mci_part *part)
>  	return 0;
>  }
>  
> +static int of_broken_cd_fixup(struct device_node *root, void *ctx)
> +{
> +	struct device_d *hw_dev = ctx;
> +	struct device_node *np;
> +	char *name;
> +
> +	name = of_get_reproducible_name(hw_dev->device_node);
> +	np = of_find_node_by_reproducible_name(root, name);
> +	free(name);
> +	if (!np) {
> +		dev_warn(hw_dev, "Cannot find nodepath %s, cannot fixup\n",
> +			 hw_dev->device_node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	of_property_write_bool(np, "cd-gpios", false);
> +	of_property_write_bool(np, "broken-cd", true);
> +
> +	return 0;
> +}
> +
>  /**
>   * Probe an MCI card at the given host interface
>   * @param mci MCI device instance
> @@ -1737,10 +1758,13 @@ static int mci_card_probe(struct mci *mci)
>  	struct mci_host *host = mci->host;
>  	int i, rc, disknum, ret;
>  
> -	if (host->card_present && !host->card_present(host) &&
> -	    !host->non_removable) {
> -		dev_err(&mci->dev, "no card inserted\n");
> -		return -ENODEV;
> +	if (host->card_present && !host->card_present(host) && !host->non_removable) {
> +		if (!IS_ENABLED(CONFIG_MCI_BROKEN_CD)) {
> +			dev_err(&mci->dev, "no card inserted\n");
> +			return -ENODEV;
> +		}
> +
> +		dev_info(&mci->dev, "no card inserted (ignoring)\n");
>  	}
>  
>  	ret = regulator_enable(host->supply);
> @@ -1818,6 +1842,10 @@ static int mci_card_probe(struct mci *mci)
>  		}
>  	}
>  
> +	if (IS_ENABLED(CONFIG_MCI_BROKEN_CD) && !host->no_sd &&
> +	    dev_of_node(host->hw_dev))
> +		of_register_fixup(of_broken_cd_fixup, host->hw_dev);

This fixup is only registered when the card is probed, i.e. when it's
used in barebox. Shouldn't it be registered in mci_register() instead?

Sascha


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