Re: [PATCH v5 1/3] memory: omap-gpmc: allow shared wait pins

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 16/09/2022 14:07, B. Niedermayr wrote:
> From: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
> 
> Newer kernels refuse to probe when using the same wait pin for
> different chipselect regions.
> But this may be a usecase when connecting for example FPGA or ASIC
> modules to the gpmc, which only got one wait pin installed.
> 
> The wait-pin allocation is now tracked by the gpmc driver in order
> to be sure that the wait pin has been indeed requested by gpmc.
> Therefore the "wait_pin_alloc_mask" has been introduced.
> 
> Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
> ---
>  drivers/memory/omap-gpmc.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
> index d9bf1c2ac319..ea495e93766b 100644
> --- a/drivers/memory/omap-gpmc.c
> +++ b/drivers/memory/omap-gpmc.c
> @@ -232,6 +232,7 @@ struct gpmc_device {
>  	int irq;
>  	struct irq_chip irq_chip;
>  	struct gpio_chip gpio_chip;
> +	unsigned long wait_pin_alloc_mask;
>  	int nirqs;
>  	struct resource *data;
>  };
> @@ -2221,9 +2222,16 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
>  							 GPIO_ACTIVE_HIGH,
>  							 GPIOD_IN);
>  		if (IS_ERR(waitpin_desc)) {
> -			dev_err(&pdev->dev, "invalid wait-pin: %d\n", wait_pin);
>  			ret = PTR_ERR(waitpin_desc);
> -			goto err;
> +			if (ret == -EBUSY &&
> +			    test_bit(wait_pin, &gpmc->wait_pin_alloc_mask)) {
> +				dev_info(&pdev->dev, "shared wait-pin: %d\n", wait_pin);
> +			} else {
> +				dev_err(&pdev->dev, "invalid wait-pin: %d\n", wait_pin);
> +				goto err;
> +			}
> +		} else {
> +			set_bit(wait_pin, &gpmc->wait_pin_alloc_mask);
>  		}

And how do you handle shared pin when the original owner unbinds?


Best regards,
Krzysztof