From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752450AbbHMNHz (ORCPT ); Thu, 13 Aug 2015 09:07:55 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:35489 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbbHMNHl (ORCPT ); Thu, 13 Aug 2015 09:07:41 -0400 Date: Thu, 13 Aug 2015 14:07:36 +0100 From: Lee Jones To: Jassi Brar Cc: "linux-arm-kernel@lists.infradead.org" , Linux Kernel Mailing List , kernel@stlinux.com, Devicetree List Subject: Re: [PATCH v2 5/6] mailbox: Add generic mechanism for testing Mailbox Controllers Message-ID: <20150813130736.GG8782@x1> References: <20150812102328.GD18282@x1> <20150813091914.GB8782@x1> <20150813102335.GC8782@x1> <20150813110008.GD8782@x1> <20150813114005.GF8782@x1> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 Aug 2015, Jassi Brar wrote: > On Thu, Aug 13, 2015 at 5:10 PM, Lee Jones wrote: > > On Thu, 13 Aug 2015, Jassi Brar wrote: > > > >> On Thu, Aug 13, 2015 at 4:30 PM, Lee Jones wrote: > >> > On Thu, 13 Aug 2015, Jassi Brar wrote: > >> > > >> >> On Thu, Aug 13, 2015 at 3:53 PM, Lee Jones wrote: > >> >> > On Thu, 13 Aug 2015, Jassi Brar wrote: > >> >> > > >> >> >> On Thu, Aug 13, 2015 at 2:49 PM, Lee Jones wrote: > >> >> >> > On Thu, 13 Aug 2015, Jassi Brar wrote: > >> >> >> > >> >> >> >> >> > + > >> >> >> >> >> > +static void mbox_test_prepare_message(struct mbox_client *client, void *message) > >> >> >> >> >> > +{ > >> >> >> >> >> > + struct mbox_test_device *tdev = dev_get_drvdata(client->dev); > >> >> >> >> >> > + > >> >> >> >> >> > + if (tdev->mmio) > >> >> >> >> >> > + memcpy(tdev->mmio, message, MBOX_MAX_MSG_LEN); > >> >> >> >> >> > > >> >> >> >> >> This is unlikely to work. Those platforms that need to send a 2 part > >> >> >> >> >> message, they do : > >> >> >> >> >> (a) Signal/Command/Target code via some controller register (via > >> >> >> >> >> mbox_send_message). > >> >> >> >> >> (b) Setup the payload in Shared-Memory (via tx_prepare). > >> >> >> >> >> > >> >> >> >> >> This test driver assumes both are the same. I think you have to > >> >> >> >> >> declare something like > >> >> >> >> > > >> >> >> >> > This driver assumes that the framework will call client->tx_prepare() > >> >> >> >> > first, which satisfies (b). It then assumes controller->send_data() > >> >> >> >> > will be invoked, which will send the platform specific > >> >> >> >> > signal/command/target code, which then satisfies (a). > >> >> >> >> > > >> >> >> >> Yeah, but what would be that code? Who provides that? > >> >> >> >> > >> >> >> >> > In what way does it assume they are the same? > >> >> >> >> > > >> >> >> >> notice the 'message' pointer in > >> >> >> >> mbox_send_message(tdev->tx_channel, message); > >> >> >> >> and > >> >> >> >> memcpy(tdev->mmio, message, MBOX_MAX_MSG_LEN); > >> >> >> >> > >> >> >> >> >> struct mbox_test_message { /* same for TX and RX */ > >> >> >> >> >> unsigned sig_len; > >> >> >> >> >> void *signal; /* rx/tx via mailbox api */ > >> >> >> >> >> unsigned pl_len; > >> >> >> >> >> void *payload; /* rx/tx via shared-memory */ > >> >> >> >> >> }; > >> >> >> >> > > >> >> >> >> > How do you think this should be set and use these? > >> >> >> >> > > >> >> >> >> The userspace would want to specify the command code (32bits or not) > >> >> >> >> that would be passed via the fifo/register of the controller. So we > >> >> >> >> need signal[] > >> >> >> >> > >> >> >> >> The data to be passed via share-memory could be provided by userspace > >> >> >> >> via the payload[] array. > >> >> >> > > >> >> >> > Okay, so would the solution be two userspace files 'signal' and > >> >> >> > 'message', so in the case of a client specified signal we can write it > >> >> >> > into there first. > >> >> >> > > >> >> >> > echo 255 > signal > >> >> >> > echo test > message > >> >> >> > > >> >> >> > ... or in the case where no signal is required, or the controller > >> >> >> > driver taking care of it, we just don't write anything to signal? > >> >> >> > > >> >> >> file_operations.write() should parse signal and message, coming from > >> >> >> userspace, into a local structure before routing them via > >> >> >> mbox_send_message and tx_prepare respectively. > >> >> > > >> >> > Okay. So before I code this up we should agree on syntax. > >> >> > > >> >> > How would you like to represent the break between signal and message? > >> >> > Obviously ' ' would be a bad idea, as some clients may want to send > >> >> > messages with white space contained. How about '\t' or '\n'? > >> >> > > >> >> Yeah, I am not a fan of markers and flags either. > >> >> > >> >> Maybe we should share with userspace > >> >> struct mbox_test_message { /* same for TX and RX */ > >> >> unsigned sig_len; > >> >> void __user *signal; /* rx/tx via mailbox api */ > >> >> unsigned pl_len; > >> >> void __user *payload; /* rx/tx via shared-memory */ > >> >> }; > >> >> > >> >> First copy_from_user the structure of length sizof(struct > >> >> mbox_test_message) and then copy_from_user length sig_len and pl_len > >> >> from signal[] and payload[] respectively (usually ioctls would carry > >> >> such data). > >> > > >> > Simplicity and ease of use should be the goals here. Testers should > >> > not have to write applications to use this driver. Can we come up > >> > with a simple/effective method that uses SYSFS/DEBUGFS please? > >> > > >> > The easiest way I can think of which avoids markers/separators AND the > >> > requirement for users to have to write applications is to have two > >> > files, 'signal' and 'message' as mentioned before. Once both are > >> > populated I can get this driver to draft the message appropriately and > >> > fire it off. > >> > > >> And then write to more files for RX data? ... which should also be in > >> the form of 'signal' and 'message'. > >> > >> BTW like for spi there is a stock application in > >> Documentation/spi/spidev_test.c we could do the same? > > > > Coming from personal experience, testing drivers with (even stock) > > applications is much more painful that simply writing/reading > > (cat/echo) to a file in SYSFS/DEBUGFS. Particularly if people are > > using initramfs or thelike. If it is possible to use SYSFS/DEBUGFS, > > which it is in this case, then I believe that's the route we could go > > down. > > > Well, where could sysfs/debugfs not be used? :) Anyways I am ok if > prefer debugfs. You know what I mean; CPIO et. al. > > In answer to your question; we only need those two files. The reply > > can be placed back into 'message' and can be read from there. > > > Testing shouldn't be restricted to 'send command and receive reply'. > What if Linux only listens to broadcasts from the remote? Who knows > someone might want to (ab)use this test client to implement userspace > handler of remote commands? > So please see RX to be independent of TX. Sure. Now just agree with me that mbox_request_chan() should fail on request of a known bad configuration request and I can code all this up and re-submit. :D -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog