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20 Jan 2023 11:16:41 -0800 Message-ID: <881088ad-95d7-2462-20d2-72a6a9d3ba68@linux.intel.com> Date: Fri, 20 Jan 2023 10:20:50 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.4.2 Subject: Re: [PATCH 2/2] soundwire: bus: Allow SoundWire peripherals to register IRQ handlers Content-Language: en-US To: Charles Keepax References: <20230119165104.3433290-1-ckeepax@opensource.cirrus.com> <20230119165104.3433290-2-ckeepax@opensource.cirrus.com> <20230120095941.GL36097@ediswmail.ad.cirrus.com> From: Pierre-Louis Bossart In-Reply-To: <20230120095941.GL36097@ediswmail.ad.cirrus.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, patches@opensource.cirrus.com, linux-kernel@vger.kernel.org, vkoul@kernel.org, sanyog.r.kale@intel.com, yung-chuan.liao@linux.intel.com Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On 1/20/23 03:59, Charles Keepax wrote: > On Thu, Jan 19, 2023 at 11:12:04AM -0600, Pierre-Louis Bossart wrote: >> No objection on this addition, just a couple of comments to improve it: >> >>> EXPORT_SYMBOL(sdw_bus_master_add); >>> @@ -158,6 +183,8 @@ static int sdw_delete_slave(struct device *dev, void *data) >>> mutex_lock(&bus->bus_lock); >>> >>> if (slave->dev_num) { /* clear dev_num if assigned */ >>> + irq_dispose_mapping(irq_find_mapping(bus->domain, slave->dev_num)); >>> + >> >> could this be done conditionally. e.g. >> >> if (slave->prop.irq) >> irq_dispose_mapping(irq_find_mapping(bus->domain, slave->dev_num)); >> >>> + slave->irq = irq_create_mapping(bus->domain, dev_num); >>> + if (!slave->irq) { >>> + dev_err(bus->dev, "Failed to map IRQ\n"); >>> + return -EINVAL; >>> + } >> >> ...and here.... >> >> if (slave->prop.irq) { >> slave->irq = irq_create_mapping(bus->domain, dev_num); >> if (!slave->irq) { >> dev_err(bus->dev, "Failed to map IRQ\n"); >> return -EINVAL; >> } >> } >> > > Yeah I am happy to make those conditional, I guess it is cleaner > to not map IRQs if they wont be used. ok > >>> @@ -369,6 +371,7 @@ struct sdw_dpn_prop { >>> * @clock_reg_supported: the Peripheral implements the clock base and scale >>> * registers introduced with the SoundWire 1.2 specification. SDCA devices >>> * do not need to set this boolean property as the registers are required. >>> + * @irq: call actual IRQ handler on slave, as well as callback >>> */ >>> struct sdw_slave_prop { >>> u32 mipi_revision; >>> @@ -393,6 +396,7 @@ struct sdw_slave_prop { >>> u8 scp_int1_mask; >>> u32 quirks; >>> bool clock_reg_supported; >>> + bool irq; >> >> this can be confused with the 'wake_capable' property. >> >> maybe 'out_of_band_irq' ? >> > > Yes I struggle on the name a bit and then just gave up and > went with plain "irq", hard to know what to call it. Not sure > out_of_band is quite right since it not really out of band, > handle_nested_irq pretty much basically boils down to a function > call really. Maybe something like "map_irq", or "use_domain_irq"? Naming is hard. I use 'in-band wake' for SoundWire-based notifications, so I used 'out-of-band' for non-SoundWire stuff. use_domain_irq sounds goods to me, it's different enough that confusions are not possible. >> There should be an explanation and something checking that both are not >> used concurrently. > > I will try to expand the explanation a litte, but I dont see any > reason to block calling both handlers, no ill effects would come > for a driver having both and it is useful if any soundwire > specific steps are needed that arn't on other control buses. I think it's problematic if the peripheral tries to wake-up the manager from clock-stop with both an in-band wake (i.e. drive the data line high) and a separate GPIO-based interrupt. It's asking for trouble IMHO. We spent hours in the MIPI team to make sure there were no races between the manager-initiated restarts and peripheral-initiated restarts, adding a 3rd mechanism in the mix gives me a migraine already.