From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 81D4E1D2F56; Tue, 6 Aug 2024 13:42:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722951728; cv=none; b=F6UNfz+GURncVUSDXT61n+987wNvmZS7pjUEqC+9TqVrbjhtBLSZVilmpZkTAtttIbJVWtzhScPtvBehdRojkphq0LLc7hxoOQDgUVjPhh9dCUu4jU7k5eFRfa4VMEgxEYELh6kADJL1gvhTh3jy6r0GUDSbSEcnuu+lRldAHkk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722951728; c=relaxed/simple; bh=pzyYkc0zT5UTgprpaHKFqWUJ4uyiWupZGk5utdJHzLw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ftbVEYdfU7z3KJCesQaJFpocGM+hYrcQufncwRkxDECaW3qxkIQVD19KfnZFm9GFKi+Og/GsGh8pwdM0WxJHWjDHcxvvEBlAq+/Zxt2rZ4z3AALXlP82U8TQfUF+nl6X1vlPrkOXt2uy+FFe6eX/0Jb0jAntyRaUV3AFEcoQyzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ACBEEFEC; Tue, 6 Aug 2024 06:42:31 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1AFD13F766; Tue, 6 Aug 2024 06:42:05 -0700 (PDT) Date: Tue, 6 Aug 2024 14:42:02 +0100 From: Sudeep Holla To: Cristian Marussi Cc: Etienne Carriere , linux-kernel@vger.kernel.org, arm-scmi@vger.kernel.org, Sudeep Holla , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] firmware: arm_scmi: fix voltage description in failure cases Message-ID: References: <20240725065317.3758165-1-etienne.carriere@foss.st.com> Precedence: bulk X-Mailing-List: linux-kernel@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: On Thu, Aug 01, 2024 at 11:58:19AM +0100, Cristian Marussi wrote: > On Fri, Jul 26, 2024 at 04:16:03PM +0100, Sudeep Holla wrote: > > On Thu, Jul 25, 2024 at 08:53:17AM +0200, Etienne Carriere wrote: > > > Reset the reception buffer max size when a voltage domain description > > > request fails, for example when the voltage domain returns an access > > > permission error (SCMI_ERR_ACCESS) unless what only a single 32bit > > > word is read back for the remaining voltage description requests > > > responses leading to invalid information. The side effect of this > > > issue is that the voltage regulators registered from those remaining > > > SCMI voltage domain were assigned a wrong regulator name. > > > > > > Signed-off-by: Etienne Carriere > > > --- > > > drivers/firmware/arm_scmi/voltage.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/firmware/arm_scmi/voltage.c b/drivers/firmware/arm_scmi/voltage.c > > > index 2175ffd6cef5..f1a7c04ae820 100644 > > > --- a/drivers/firmware/arm_scmi/voltage.c > > > +++ b/drivers/firmware/arm_scmi/voltage.c > > > @@ -229,8 +229,10 @@ static int scmi_voltage_descriptors_get(const struct scmi_protocol_handle *ph, > > > /* Retrieve domain attributes at first ... */ > > > put_unaligned_le32(dom, td->tx.buf); > > > /* Skip domain on comms error */ > > > - if (ph->xops->do_xfer(ph, td)) > > > + if (ph->xops->do_xfer(ph, td)) { > > > + ph->xops->reset_rx_to_maxsz(ph, td); > > > > I am fine with this to keep it simple, but thought I will check my thoughts. > > We usually use reset_rx_to_maxsz in iterators as we don't know the expected > > size of the response, whereas here it must be max sizeof(*resp_dom). > > > > That said, we don't have any helpers and changing xfer->rx.len directly > > doesn't looks good ? Or may be it is OK ? Thoughts ? > > We do not access those xfer internal field explicitly from the protocol layer > (beside once in Base)...and surely not on write....in the past I was even > tempted to try to make these internal stuff untouchable by the protocol layer... > ...that's the reason of course for the existence of reset_rx_to_maxsz() helpers > ....not sure if it is worth adding another helper for this, given that the > using the maxsz should have any adverse effect (unless I am missing > something of course :P). > > This kind of 'issues' are really common whenever in the SCMI stack we > reuse the same allocated xfer across multiple do_xfers in a loop > (reusing seq_nums is another thing...) since we wanted to avoid the > penalty of resetting some of these automatically on each do_xfer()... > > ....we could think of some mechanism to transparently reset/fill such xfer > fields automatically if the core detects a 'reuse'....got to check first, > though, if this does not break some of the current usage patterns...and > I would not say it is a high prio thing to explore as of now... > Fair enough, I will merge this as is. I think it should be fine. My suggestion might simply complicates things unnecessarily. Lets not do it unless this becomes repeating pattern. -- Regards, Sudeep