netdev - Re: [PATCH net 1/7] atlantic: Increase delay for fw transactions

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Date:   Tue, 30 Nov 2021 03:48:10 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Sudarsana Reddy Kalluru <skalluru@...vell.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, irusskikh@...vell.com,
        dbezrukov@...vell.com
Subject: Re: [PATCH net 1/7] atlantic: Increase delay for fw transactions

On Mon, Nov 29, 2021 at 05:28:23AM -0800, Sudarsana Reddy Kalluru wrote:
> From: Dmitry Bogdanov <dbezrukov@...vell.com>
> 
> The max waiting period (of 1 ms) while reading the data from FW shared
> buffer is too small for certain types of data (e.g., stats). There's a
> chance that FW could be updating buffer at the same time and driver
> would be unsuccessful in reading data. Firmware manual recommends to
> have 1 sec timeout to fix this issue.
> 
> Fixes: 5cfd54d7dc186 ("net: atlantic: minimal A2 fw_ops")
> Signed-off-by: Dmitry Bogdanov <dbezrukov@...vell.com>
> Signed-off-by: Sudarsana Reddy Kalluru <skalluru@...vell.com>
> Signed-off-by: Igor Russkikh <irusskikh@...vell.com>
> ---
>  .../ethernet/aquantia/atlantic/hw_atl2/hw_atl2_utils_fw.c  | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/aquantia/atlantic/hw_atl2/hw_atl2_utils_fw.c b/drivers/net/ethernet/aquantia/atlantic/hw_atl2/hw_atl2_utils_fw.c
> index dd259c8f2f4f..b0e4119b9883 100644
> --- a/drivers/net/ethernet/aquantia/atlantic/hw_atl2/hw_atl2_utils_fw.c
> +++ b/drivers/net/ethernet/aquantia/atlantic/hw_atl2/hw_atl2_utils_fw.c
> @@ -84,7 +84,7 @@ static int hw_atl2_shared_buffer_read_block(struct aq_hw_s *self,
>  			if (cnt > AQ_A2_FW_READ_TRY_MAX)
>  				return -ETIME;
>  			if (tid1.transaction_cnt_a != tid1.transaction_cnt_b)
> -				udelay(1);
> +				mdelay(1);
>  		} while (tid1.transaction_cnt_a != tid1.transaction_cnt_b);

This change is the 1 second timeout.

>  
>  		hw_atl2_mif_shared_buf_read(self, offset, (u32 *)data, dwords);
> @@ -339,8 +339,11 @@ static int aq_a2_fw_update_stats(struct aq_hw_s *self)
>  {
>  	struct hw_atl2_priv *priv = (struct hw_atl2_priv *)self->priv;
>  	struct statistics_s stats;
> +	int err;
>  
> -	hw_atl2_shared_buffer_read_safe(self, stats, &stats);
> +	err = hw_atl2_shared_buffer_read_safe(self, stats, &stats);
> +	if (err)
> +		return err;

This change however does not seem to be explained in the commit
message. Not discarding an error is a good change, but it needs
commenting on.

Also, looking at hw_atl2_shared_buffer_read_block() i notice it
returns -ETIME. It should be -ETIMEDOUT.

	Andrew