From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 254E6C61DA4 for ; Thu, 16 Feb 2023 22:24:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229965AbjBPWYx (ORCPT ); Thu, 16 Feb 2023 17:24:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229571AbjBPWYv (ORCPT ); Thu, 16 Feb 2023 17:24:51 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18BE8FC for ; Thu, 16 Feb 2023 14:24:50 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BBBFEB829D3 for ; Thu, 16 Feb 2023 22:24:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2EE29C433EF; Thu, 16 Feb 2023 22:24:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676586287; bh=AkZM/C98uZwsgM85uiCRPO8EwcX7/vGb5dRzoigiFTA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=h4twjsHpYg1ZsRqwRiklnPfq4ZL4PLdfXIOwL4h/BMGngn3raqEE+AFRX1+MzO+rI 9kdpAw/cISlY2uNSKIhFBvBn+9/Vg0MXjApHlpFLECWOBFDKeAKjoZP01mgOBwqt0x FuOnjxyytzEFmLvfvBcf5v/oEbAjvwWy1RhdiMo1WPmzZXMJUwmkAzUFYYIbSGd5UW 3obfXS5e3o6e91XRY//h/6oZEjzpS80cQzgtzbmxQAund+ojjNesgnCP2pi3Nyjc8v +j362C3E0UB1uIZH/wFy21eps9zuTshDeDXbsn/7ySECxAmJc2lHMzXJhVSG6CTi/F CwijcSlo/c7eg== Date: Thu, 16 Feb 2023 22:24:43 +0000 From: Conor Dooley To: Jassi Brar Cc: Conor Dooley , Daire McNamara , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 0/7] MPFS system controller/mailbox fixes Message-ID: References: <20230111134513.2495510-1-conor.dooley@microchip.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cHIZQMqJK0RslrQL" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --cHIZQMqJK0RslrQL Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hey Jassi, On Sat, Jan 21, 2023 at 07:12:52PM +0000, Conor Dooley wrote: > On Sat, Jan 21, 2023 at 10:01:41AM -0600, Jassi Brar wrote: > > On Wed, Jan 11, 2023 at 7:45 AM Conor Dooley wrote: > > > > > > In order to differentiate between the service succeeding & the system > > > controller being inoperative or otherwise unable to function, I had to > > > switch the controller to poll a busy bit in the system controller's > > > registers to see if it has completed a service. > > > This makes sense anyway, as the interrupt corresponds to "data ready" > > > rather than "tx done", so I have changed the mailbox controller driver > > > to do that & left the interrupt solely for signalling data ready. > > > It just so happened that all of the services that I had worked with a= nd > > > tested up to this point were "infallible" & did not set a status, so = the > > > particular code paths were never tested. > > > > > > Jassi, the mailbox and soc patches depend on each other, as the change > > > in what the interrupt is used for requires changing the client driver= 's > > > behaviour too, as mbox_send_message() will now return when the system > > > controller is no longer busy rather than when the data is ready. > > > I'm happy to send the lot via the soc tree with your Ack and/or reive= w, > > > if that also works you? > > > > > Ok, let me review them and get back to you. >=20 > FYI, I did sent a v2 on Friday: > https://lore.kernel.org/all/20230120143734.3438755-1-conor.dooley@microch= ip.com/ >=20 > The change is just a timeout duration though. >=20 > > > Secondly, I have a question about what to do if a service does fail, = but > > > not due to a timeout - eg the above example where the "new" image for > > > the FPGA is actually older than the one that currently exists. > > > Ideally, if a service fails due to something other than the transacti= on > > > timing out, I would go and read the status registers to see what the > > > cause of failure was. > > > I could not find a function in the mailbox framework that allows the > > > client to request that sort of information from the client. Trying to > > > do something with the auxiliary bus, or exporting some function to a > > > device specific header seemed like a circumvention of the mailbox > > > framework. > > > Do you think it would be a good idea to implement something like > > > mbox_client_peek_status(struct mbox_chan *chan, void *data) to allow > > > clients to request this type of information? > > > > > .last_tx_done() is supposed to make sure everything is ok. >=20 > Hm, might've explained badly as I think you've misunderstood. Or (see > below) I might have mistakenly thought that last_tx_done() was only meant > to signify that tx was done. >=20 > Anyways, I'll try to clarify. > Some services don't set a status, but whether a status is, or isn't, > set has nothing to do with whether the service has completed. > One service that sets a status is "Authenticate Bitstream". This > service sets a status of 0x0 if the bitstream in question is okay _and_ > something that the FPGA can be upgraded to. It returns a failure of 0x18 > if the bitstream is valid _but_ is the same as that currently programmed. > (and of course a whole host of other possible errors in-between) >=20 > These statuses, and whether they are a bad outcome or not, is dependant > on the service and I don't think should be handled in the mailbox > controller driver. >=20 > > If the expected status bit is "sometimes not set", that means that bit > > is not the complete status. >=20 > If the "busy" bit goes low, then the transmission must be complete, > there should be no need to check other bits for *completion*, but... >=20 > > You have to check multiple registers to > > detect if and what caused the failure. >=20 > ...maybe I have just misunderstood the role of .last_tx_done(). The > comment in mailbox-controller.h lead me to believe that it was used just > to check if it had been completed. >=20 > Am I allowed to use .last_tx_done() to pass information back to the > mailbox client? If I could, that'd certainly be a nice way to get the > information on whether the service failed etc. >=20 > Hopefully that, plus when you have a chance to look at the code, will > make what I am asking about a little clearer! Just wondering if you've had a chance to look at this again! I know it's missed the merge window this time around but I would like to get this behaviour fixed as other work depends on it. Thanks, Conor. --cHIZQMqJK0RslrQL Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCY+6tKwAKCRB4tDGHoIJi 0l6cAQCsWrIH+pqBwAf69uZLhrJvtlpPqSCTYxGM7EMsGHBwnQD+OgimOQeWf7mr 9KgBmT+TJwYcmQ2Rk1rSxiDu3y+fhgo= =AfHa -----END PGP SIGNATURE----- --cHIZQMqJK0RslrQL--