Subject: Re: [PATCH 2/2] wcn36xx: fix RX BD rate mapping for 5GHz legacy rates

From: Kalle Valo <[email-masked]>
Date: Mon, 01 Nov 2021 15:00:30 +0200

Benjamin Li <[email-masked]> writes:

> On 10/28/21 5:30 PM, Bryan O'Donoghue wrote:
>> On 28/10/2021 23:31, Benjamin Li wrote:
>>> -            status.rate_idx >= sband->n_bitrates) {
>> This fix was applied because we were getting a negative index
>> 
>> If you want to remove that, you'll need to do something about this
>> 
>> status.rate_idx -= 4;
>
> Hmm... so you're saying there's a FW bug where sometimes we get
> bd->rate_id = 0-7 (leading to status.rate_idx = 0-3) on a 5GHz
> channel?
>
> static const struct wcn36xx_rate wcn36xx_rate_table[] = {
>     /* 11b rates */
>     {  10, 0, RX_ENC_LEGACY, 0, RATE_INFO_BW_20 },
>     {  20, 1, RX_ENC_LEGACY, 0, RATE_INFO_BW_20 },
>     {  55, 2, RX_ENC_LEGACY, 0, RATE_INFO_BW_20 },
>     { 110, 3, RX_ENC_LEGACY, 0, RATE_INFO_BW_20 },
>
>     /* 11b SP (short preamble) */
>     {  10, 0, RX_ENC_LEGACY, RX_ENC_FLAG_SHORTPRE, RATE_INFO_BW_20 },
>     {  20, 1, RX_ENC_LEGACY, RX_ENC_FLAG_SHORTPRE, RATE_INFO_BW_20 },
>     {  55, 2, RX_ENC_LEGACY, RX_ENC_FLAG_SHORTPRE, RATE_INFO_BW_20 },
>     { 110, 3, RX_ENC_LEGACY, RX_ENC_FLAG_SHORTPRE, RATE_INFO_BW_20 },
>
> It sounds like we should WARN and drop the frame in that case. If
> you agree I'll send a v2.

BTW, please avoid using WARN() family of functions in the data path as
that can cause host crashes due to too much spamming in the logs. A some
kind of ratelimited version of an error message is much safer. For
example ath11k_warn() is ratelimited, maybe wcn36xx_warn() should be as
well?

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