From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 546AB1386A7 for ; Wed, 4 Sep 2024 20:20:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725481239; cv=none; b=fZGAMCOqIfExBuaz+h287xE5ygpio4a44yAVRhtTdXY8SsyrJ51o+lwCZx5NTusPIy7IKPRjM7W6GoVifd/YbkluW7mKcdNhIa1C4tvzel0hrT14Qv/qJL+CjAlEUN+4xws6CaToxi2U8yEOu3bB5E14HkZwEvYMC3JsvMgX2OI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725481239; c=relaxed/simple; bh=Sg43O1ePYPQ9Cq/7OpArLSkv1jO6W47q7rmWSH/67LE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uCgusk8I+O+KFbcGEsO0VmUxlK2qiO3bKxFxiGtnUXs9tUHT2i6q1CgK1m1JuCQhDoqcM9p7oLQwO5Rc8yCxVYPfjeqQMeFb7Ha0J6HyHc286EAwkX6IIbTkw/2idMVBM0rNzxEeNNv3yptc9UbthrGr6QZRA8I8iCq6shwx/BM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=beAnG/KO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="beAnG/KO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 732B3C4CEC2; Wed, 4 Sep 2024 20:20:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1725481238; bh=Sg43O1ePYPQ9Cq/7OpArLSkv1jO6W47q7rmWSH/67LE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=beAnG/KOvH+K8qbo9uuB7urjvtKApfKwcEzey/pfb9OT+duyVH8o4X+UqNehaBjvq kYiuwUTyp4Jw1ZQBDV5KCzzamj38NQAhPotZEi51YBixWpIqEbM1R01xSnE9GUrl/B WF0xjkF/5c2VA3Xs90Pr1p19RchLOMVi7ciT6LX3yJN8fOuM9XnrbvgSyO4BZyudoS GuwSDWHKJy85fNA3py2HrOVw0HqtemATIPKnYNSr+xshChN4H8jaX9AWAuPgYdr6yc OHV+TiFCRFvh89pXZBef19N8rIlf7A8J4LMPybNgs7EkQdTx/johzXWQNdQeBVC2IG m6V4NdaWeWorQ== Date: Wed, 4 Sep 2024 21:20:35 +0100 From: Simon Horman To: Vadim Fedorenko Cc: Jakub Kicinski , Jonathan Lemon , Paolo Abeni , David Ahern , netdev@vger.kernel.org Subject: Re: [PATCH net-next] ptp: ocp: Improve PCIe delay estimation Message-ID: <20240904202035.GF1722938@kernel.org> References: <20240904132842.559217-1-vadim.fedorenko@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240904132842.559217-1-vadim.fedorenko@linux.dev> On Wed, Sep 04, 2024 at 01:28:42PM +0000, Vadim Fedorenko wrote: > The PCIe bus can be pretty busy during boot and probe function can > see excessive delays. Let's find the minimal value out of several > tests and use it as estimated value. > > Signed-off-by: Vadim Fedorenko > --- > drivers/ptp/ptp_ocp.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c > index e7479b9b90cb..22b22e605781 100644 > --- a/drivers/ptp/ptp_ocp.c > +++ b/drivers/ptp/ptp_ocp.c > @@ -1561,19 +1561,22 @@ ptp_ocp_estimate_pci_timing(struct ptp_ocp *bp) > ktime_t start, end; > ktime_t delay; > u32 ctrl; > + int i; > > - ctrl = ioread32(&bp->reg->ctrl); > - ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; > + for (i = 0; i < 3; i++) { > + ctrl = ioread32(&bp->reg->ctrl); > + ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; > > - iowrite32(ctrl, &bp->reg->ctrl); > + iowrite32(ctrl, &bp->reg->ctrl); > > - start = ktime_get_ns(); > + start = ktime_get_ns(); > > - ctrl = ioread32(&bp->reg->ctrl); > + ctrl = ioread32(&bp->reg->ctrl); > > - end = ktime_get_ns(); > + end = ktime_get_ns(); > > - delay = end - start; > + delay = min(delay, end - start); Hi Vadim, It looks like delay is used uninitialised here in the first iteration of this loop. Flagged by Smatch. > + } > bp->ts_window_adjust = (delay >> 5) * 3; > } > > -- > 2.43.0 > >