diff mbox series

[v4,1/3] memory: omap-gpmc: allow shared wait pins

Message ID 20220915091333.2425306-2-benedikt.niedermayr@siemens.com
State New
Headers show
Series omap-gpmc wait pin additions | expand

Commit Message

B. Niedermayr Sept. 15, 2022, 9:13 a.m. UTC 
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.

Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
---
 drivers/memory/omap-gpmc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Comments

Roger Quadros Sept. 16, 2022, 8:50 a.m. UTC | #1 
Hi,

On 15/09/2022 12:13, 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.
> 
> Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
> ---
>  drivers/memory/omap-gpmc.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
> index d9bf1c2ac319..e3674a15b934 100644
> --- a/drivers/memory/omap-gpmc.c
> +++ b/drivers/memory/omap-gpmc.c
> @@ -2221,9 +2221,13 @@ 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) {
> +				dev_info(&pdev->dev, "shared wait-pin: %d\n", wait_pin);

What if this GPI was taken by someone other than us for wait-pin usage?
e.g. some other device driver for GPI usage?

In that case that GPIO functionality will break if we now start using it for wait-pin usage. Right?

One solution could be keep track if we reserved that pin for wait-pin usage
and if so sharing the wait-pin for wait-pin usage is fine.

> +			} else {
> +				dev_err(&pdev->dev, "invalid wait-pin: %d\n", wait_pin);
> +				goto err;
> +			}
>  		}
>  	}
>  

cheers,
-roger
diff mbox series

Patch

diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
index d9bf1c2ac319..e3674a15b934 100644
--- a/drivers/memory/omap-gpmc.c
+++ b/drivers/memory/omap-gpmc.c
@@ -2221,9 +2221,13 @@  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) {
+				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;
+			}
 		}
 	}