Re: [PATCH v2] fpga: altera-cvp: allow interrupt to continue next time

From: Xu Yilun
Date: Fri Jun 03 2022 - 07:08:46 EST


On Wed, Jun 01, 2022 at 09:40:27AM +0800, tien.sung.ang@xxxxxxxxx wrote:
> From: Dinh Nguyen <dinh.nguyen@xxxxxxxxx>
>
> The main objective of this change is to perform error handling
> if the CvP firmware becomes unresponsive. The error_path flow
> resets the CvP mode and HIP_CLK_SEL bit.
>
> CFG_READY signal/bit may time-out due to firmware not responding
> within the given time-out. This time varies due to numerous
> factors like size of bitstream and others.
> This time-out error may or may not impact the result of the CvP
> previous transactions. The CvP driver shall then, respond with
> EAGAIN instead Time out error.
>
> Signed-off-by: Dinh Nguyen <dinh.nguyen@xxxxxxxxx>
> Signed-off-by: Ang Tien Sung <tien.sung.ang@xxxxxxxxx>
> ---
>
> changelog v2:
> * Amend the commit message
>
> ---
> drivers/fpga/altera-cvp.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 4ffb9da537d8..d74ff63c61e8 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -309,10 +309,22 @@ static int altera_cvp_teardown(struct fpga_manager *mgr,
> /* STEP 15 - poll CVP_CONFIG_READY bit for 0 with 10us timeout */
> ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY, 0,
> conf->priv->poll_time_us);
> - if (ret)
> + if (ret) {
> dev_err(&mgr->dev, "CFG_RDY == 0 timeout\n");
> + goto error_path;

I assume the error handling is specific to CFG_RDY timeout, is it? Then it
could be embedded in this code block.

And also the -EAGAIN ret, please only return it in this code block.

Usually the goto error path is for common fail out.

> + }
>
> return ret;
> +
> +error_path:
> + /* reset CVP_MODE and HIP_CLK_SEL bit */
> + altera_read_config_dword(conf, VSE_CVP_MODE_CTRL, &val);
> + val &= ~VSE_CVP_MODE_CTRL_HIP_CLK_SEL;
> + val &= ~VSE_CVP_MODE_CTRL_CVP_MODE;
> + altera_write_config_dword(conf, VSE_CVP_MODE_CTRL, val);
> +
> + return -EAGAIN;

Please still specify the reason for -EAGAIN rather than timeout.

Thanks,
Yilun

> +
> }
>
> static int altera_cvp_write_init(struct fpga_manager *mgr,
> --
> 2.25.1