linux-kernel - Re: [PATCH v4 4/5] fpga manager: xilinx-spi: add error checking after gpiod_get

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Message-ID: <20200831000935.GD7421@epycbox.lan>
Date:   Sun, 30 Aug 2020 17:09:35 -0700
From:   Moritz Fischer <mdf@...nel.org>
To:     Luca Ceresoli <luca@...aceresoli.net>
Cc:     linux-fpga@...r.kernel.org, Moritz Fischer <mdf@...nel.org>,
        Tom Rix <trix@...hat.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anatolij Gustschin <agust@...x.de>
Subject: Re: [PATCH v4 4/5] fpga manager: xilinx-spi: add error checking
 after gpiod_get_value()

On Sun, Aug 30, 2020 at 06:38:49PM +0200, Luca Ceresoli wrote:
> Current code calls gpiod_get_value() without error checking. Should the
> GPIO controller fail, execution would continue without any error message.
> 
> Fix by checking for negative error values.
> 
> Reported-by: Tom Rix <trix@...hat.com>
> Reviewed-by: Tom Rix <trix@...hat.com>
> Signed-off-by: Luca Ceresoli <luca@...aceresoli.net>
> 
> ---
> 
> Changes in v4:
>  - add Reviewed-by Tom Rix
> 
> Changes in v3:
>  - rebase on previous patches
> 
> This patch is new in v2
> ---
>  drivers/fpga/xilinx-spi.c | 35 +++++++++++++++++++++++++++--------
>  1 file changed, 27 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
> index fba8eb4866a7..52aab5a1f0ba 100644
> --- a/drivers/fpga/xilinx-spi.c
> +++ b/drivers/fpga/xilinx-spi.c
> @@ -27,11 +27,22 @@ struct xilinx_spi_conf {
>  	struct gpio_desc *done;
>  };
>  
> -static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
> +static int get_done_gpio(struct fpga_manager *mgr)
>  {
>  	struct xilinx_spi_conf *conf = mgr->priv;
> +	int ret;
> +
> +	ret = gpiod_get_value(conf->done);
> +
> +	if (ret < 0)
> +		dev_err(&mgr->dev, "Error reading DONE (%d)\n", ret);
>  
> -	if (!gpiod_get_value(conf->done))
> +	return ret;
> +}
> +
> +static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
> +{
> +	if (!get_done_gpio(mgr))
>  		return FPGA_MGR_STATE_RESET;
>  
>  	return FPGA_MGR_STATE_UNKNOWN;
> @@ -57,10 +68,21 @@ static int wait_for_init_b(struct fpga_manager *mgr, int value,
>  
>  	if (conf->init_b) {
>  		while (time_before(jiffies, timeout)) {
> -			if (gpiod_get_value(conf->init_b) == value)
> +			int ret = gpiod_get_value(conf->init_b);
> +
> +			if (ret == value)
>  				return 0;
> +
> +			if (ret < 0) {
> +				dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
> +				return ret;
> +			}
> +
>  			usleep_range(100, 400);
>  		}
> +
> +		dev_err(&mgr->dev, "Timeout waiting for INIT_B to %s\n",
> +			value ? "assert" : "deassert");
>  		return -ETIMEDOUT;
>  	}
>  
> @@ -85,7 +107,6 @@ static int xilinx_spi_write_init(struct fpga_manager *mgr,
>  
>  	err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
>  	if (err) {
> -		dev_err(&mgr->dev, "INIT_B pin did not go low\n");
>  		gpiod_set_value(conf->prog_b, 0);
>  		return err;
>  	}
> @@ -93,12 +114,10 @@ static int xilinx_spi_write_init(struct fpga_manager *mgr,
>  	gpiod_set_value(conf->prog_b, 0);
>  
>  	err = wait_for_init_b(mgr, 0, 0);
> -	if (err) {
> -		dev_err(&mgr->dev, "INIT_B pin did not go high\n");
> +	if (err)
>  		return err;
> -	}
>  
> -	if (gpiod_get_value(conf->done)) {
> +	if (get_done_gpio(mgr)) {
>  		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
>  		return -EIO;
>  	}
> -- 
> 2.28.0
> 
Applied to for-next,

Thanks