Return-path: Received: from mail-wi0-f174.google.com ([209.85.212.174]:36557 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792AbaCZHSV convert rfc822-to-8bit (ORCPT ); Wed, 26 Mar 2014 03:18:21 -0400 Received: by mail-wi0-f174.google.com with SMTP id d1so4364016wiv.7 for ; Wed, 26 Mar 2014 00:18:20 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <53319D65.4090907@candelatech.com> References: <1395428150-31996-1-git-send-email-greearb@candelatech.com> <871txr7svw.fsf@kamboji.qca.qualcomm.com> <53306239.2020006@candelatech.com> <53319D65.4090907@candelatech.com> Date: Wed, 26 Mar 2014 08:18:20 +0100 Message-ID: (sfid-20140326_081826_275968_BFB4950F) Subject: Re: [PATCH 1/3] ath10k: Add debugging for tx-credits usage. From: Michal Kazior To: Ben Greear Cc: Kalle Valo , linux-wireless , "ath10k@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 25 March 2014 16:14, Ben Greear wrote: > On 03/25/2014 12:27 AM, Michal Kazior wrote: >> >> On 24 March 2014 17:50, Ben Greear wrote: >>> >>> On 03/24/2014 04:21 AM, Michal Kazior wrote: >>>> >>>> On 24 March 2014 12:12, Kalle Valo wrote: >>> >>> >>>>>> - status = ath10k_htc_send(htc, ATH10K_HTC_EP_0, skb); >>>>>> + status = ath10k_htc_send(htc, ATH10K_HTC_EP_0, skb, __LINE__); >>>>> >>>>> >>>>> Using line numbers in debug messages is very cumbersome. Some people >>>>> cherry pick patches, have their own changes and whatnot which will make >>>>> it more difficult to read the debug logs. Isn't there any better way to >>>>> do this? >>>> >>>> >>>> I would prefer to explicitly wait for tx credit replenishment in >>>> ath10k_wmi_cmd_send() after a command is sent instead of all these >>>> prints. This way you can get a full call trace if it times out. >>> >>> >>> Would that be a performance problem (by effectively allowing only a >>> single >>> item to be sent to the firmware at any given time?) >> >> >> The only thing that may suffer here is wmi mgmt tx but I wouldn't >> consider that performance critical. > > > In that case, why use credits at all? Excellent question. Firmware provides 2 HTC tx credits for WMI. I guess this is on purpose. I imagine WMI mgmt tx can hang (i.e. not replenish tx credits). In that case the remaining tx credit could be used to try recovering, e.g. down/stop vdev (I think it should drop all pending tx and thus free the stuck HTC tx credit). It might be a good idea to keep this recovery strategy in mind when implementing the "wait for tx replenishment" wmi tx blocking. Michał