Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933510AbbGURs6 (ORCPT ); Tue, 21 Jul 2015 13:48:58 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:37761 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933392AbbGURs4 (ORCPT ); Tue, 21 Jul 2015 13:48:56 -0400 Date: Tue, 21 Jul 2015 18:48:51 +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 3/6] mailbox: Add support for ST's Mailbox IP Message-ID: <20150721174851.GP3061@x1> References: <1437134647-28298-1-git-send-email-lee.jones@linaro.org> <1437134647-28298-4-git-send-email-lee.jones@linaro.org> <20150721150629.GJ3061@x1> <20150721155253.GN3061@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 Content-Length: 4639 Lines: 103 On Tue, 21 Jul 2015, Jassi Brar wrote: > On Tue, Jul 21, 2015 at 9:22 PM, Lee Jones wrote: > > On Tue, 21 Jul 2015, Jassi Brar wrote: > > > >> > > >> >> > +static int sti_mbox_send_data(struct mbox_chan *chan, void *data) > >> >> > +{ > >> >> > + struct sti_channel *chan_info = chan->con_priv; > >> >> > + struct sti_mbox_device *mdev = chan_info->mdev; > >> >> > + struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev); > >> >> > + unsigned int instance = chan_info->instance; > >> >> > + unsigned int channel = chan_info->channel; > >> >> > + void __iomem *base; > >> >> > + > >> >> > + if (!sti_mbox_tx_is_ready(chan)) > >> >> > + return -EBUSY; > >> >> This is the first thing I look out for in every new driver :) this > >> >> check is unnecessary. > >> > > >> > In what way? What if the channel is disabled or there is an IRQ > >> > already pending? > >> > > >> API calls send_data() only if last_tx_done() returned true. > > > > I know for a fact that the 'catchers' in sti_mbox_tx_is_ready() to > > fire, because I have triggered them. I'd really rather keep this > > harmless check in. > > > If you put some printk in send_data() and last_tx_done() you'll see > what I mean :) > > >> >> > +static const struct sti_mbox_pdata mbox_stih407_pdata = { > >> >> > + .num_inst = 4, > >> >> > + .num_chan = 32, > >> >> > + .irq_val = 0x04, > >> >> > + .irq_set = 0x24, > >> >> > + .irq_clr = 0x44, > >> >> > + .ena_val = 0x64, > >> >> > + .ena_set = 0x84, > >> >> > + .ena_clr = 0xa4, > >> >> > > >> >> Register offsets are parameters of the controller > >> > > >> > And this is a controller driver? Not sure I get the point. > >> > > >> Platform_data usually carries board/platform specific parameters. > >> Register offset "properties" are as fixed as the behavior of the > >> controller, so they should stay inside the code, not come via > >> platform_data. > > > > That's not the case for this controller. There is nothing preventing > > these values from changing on a new board revisions. > > > Hmm ... interesting! Can't see how enable/disable channel and irq > set/clear could be effected by writing to random, but agreed upon, > location between two processors. There ought to be some controller > listening there? Now I am more interested in knowing this IP :) High level ---------- MB0 MB1 MB2 MB3 MB4 +---------+---------+---------+---------+---------+ INST0 | | | | | | +---------+---------+---------+---------+---------+ INST1 | | | | | | +---------+---------+---------+---------+---------+ INST2 | | | | | | +---------+---------+---------+---------+---------+ INST3 | | | | | | +---------+---------+---------+---------+---------+ Low level [each box above looks like this) ------------------------------------------ 1 32 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IRQ_VAL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IRQ_SET | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IRQ_CLR | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ENB_VAL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ENB_SET | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ENB_CLR | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ That's it. That's the entirety of the "IP". -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/