From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: [alsa-devel] [RFC PATCH 2/7] soundwire: add Slave sysfs support Date: Tue, 7 May 2019 08:54:28 -0500 Message-ID: References: <20190504010030.29233-1-pierre-louis.bossart@linux.intel.com> <20190504010030.29233-3-pierre-louis.bossart@linux.intel.com> <20190504065444.GC9770@kroah.com> <20190506151953.GA13178@kroah.com> <20190506162208.GI3845@vkoul-mobl.Dlink> <20190507051959.GC16052@vkoul-mobl> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190507051959.GC16052@vkoul-mobl> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Vinod Koul Cc: alsa-devel@alsa-project.org, tiwai@suse.de, Greg KH , linux-kernel@vger.kernel.org, liam.r.girdwood@linux.intel.com, broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, joe@perches.com, Sanyog Kale List-Id: alsa-devel@alsa-project.org On 5/7/19 12:19 AM, Vinod Koul wrote: > On 06-05-19, 11:46, Pierre-Louis Bossart wrote: >> On 5/6/19 11:22 AM, Vinod Koul wrote: >>> On 06-05-19, 17:19, Greg KH wrote: >>>> On Mon, May 06, 2019 at 09:42:35AM -0500, Pierre-Louis Bossart wrote: >>>>>>> + >>>>>>> +int sdw_sysfs_slave_init(struct sdw_slave *slave) >>>>>>> +{ >>>>>>> + struct sdw_slave_sysfs *sysfs; >>>>>>> + unsigned int src_dpns, sink_dpns, i, j; >>>>>>> + int err; >>>>>>> + >>>>>>> + if (slave->sysfs) { >>>>>>> + dev_err(&slave->dev, "SDW Slave sysfs is already initialized\n"); >>>>>>> + err = -EIO; >>>>>>> + goto err_ret; >>>>>>> + } >>>>>>> + >>>>>>> + sysfs = kzalloc(sizeof(*sysfs), GFP_KERNEL); >>>>>> >>>>>> Same question as patch 1, why a new device? >>>>> >>>>> yes it's the same open. In this case, the slave devices are defined at a >>>>> different level so it's also confusing to create a device to represent the >>>>> slave properties. The code works but I am not sure the initial directions >>>>> are correct. >>>> >>>> You can just make a subdir for your attributes by using the attribute >>>> group name, if a subdirectory is needed just to keep things a bit more >>>> organized. >>> >>> The key here is 'a subdir' which is not the case here. We did discuss >>> this in the initial patches for SoundWire which had sysfs :) >>> >>> The way MIPI disco spec organized properties, we have dp0 and dpN >>> properties each of them requires to have a subdir of their own and that >>> was the reason why I coded it to be creating a device. >> >> Vinod, the question was not for dp0 and dpN, it's fine to have >> subdirectories there, but rather why we need separate devices for the master >> and slave properties. > > Slave does not have a separate device. IIRC the properties for Slave are > in /sys/bus/soundwire/device//... I am not sure this is correct ACPI defines the slaves devices under /sys/bus/acpi/PRP0001, e.g. /sys/bus/acpi/devices/PRP00001:00/device:17# ls adr mipi-sdw-dp-5-sink-subproperties intel-endpoint-descriptor-0 mipi-sdw-dp-6-source-subproperties intel-endpoint-descriptor-1 mipi-sdw-dp-7-sink-subproperties mipi-sdw-dp-0-subproperties mipi-sdw-dp-8-source-subproperties mipi-sdw-dp-1-sink-subproperties path mipi-sdw-dp-1-source-subproperties physical_node mipi-sdw-dp-2-sink-subproperties power mipi-sdw-dp-2-source-subproperties subsystem mipi-sdw-dp-3-sink-subproperties uevent mipi-sdw-dp-4-source-subproperties but the sysfs for slaves is shown as /sys/bus/acpi/devices/PRP00001:00/int-sdw.0/sdw:0:25d:700:0:0# ls bank_delay_support master_count sink_ports ch_prep_timeout mipi_revision source_ports clk_stop_mode1 modalias src-dp2 clk_stop_timeout p15_behave src-dp4 dp0 paging_support subsystem driver power test_mode_capable firmware_node reset_behave uevent hda_reg simple_clk_stop_capable wake_capable high_PHY_capable sink-dp1 index_reg sink-dp3 and in sys/bus/soundwire/devices/sdw:0:25d:700:0:0# ls bank_delay_support master_count sink_ports ch_prep_timeout mipi_revision source_ports clk_stop_mode1 modalias src-dp2 clk_stop_timeout p15_behave src-dp4 dp0 paging_support subsystem driver power test_mode_capable firmware_node reset_behave uevent hda_reg simple_clk_stop_capable wake_capable high_PHY_capable sink-dp1 index_reg sink-dp3 So I would think we *do* create a new device for each slave instead of using the one that's already exposed by ACPI. > > For master yes we can skip the device creation, it was done for > consistency sake of having these properties ties into sys/bus/soundwire/ > > I don't mind if they are shown up in respective device node (PCI/platform > etc) /sys/bus/foo/device/<> > > But for creating subdirectories you would need the new dpX devices. yes, that's agreed.