Messages in this thread | | | Subject | Re: [PATCH] soundwire: debugfs: use controller id instead of link_id | From | Pierre-Louis Bossart <> | Date | Tue, 2 Feb 2021 10:43:14 -0600 |
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On 2/1/21 10:18 PM, Vinod Koul wrote: > On 01-02-21, 10:10, Pierre-Louis Bossart wrote: >> On 2/1/21 4:14 AM, Vinod Koul wrote: >>> On 21-01-21, 17:23, Srinivas Kandagatla wrote: >>>> On 21/01/2021 15:12, Pierre-Louis Bossart wrote: >>>>> On 1/21/21 6:03 AM, Srinivas Kandagatla wrote: > >>>> I totally agree! >>>> >>>> If I understand it correctly in Intel case there will be only one Link ID >>>> per bus. >>> >>> Yes IIUC there would be one link id per bus. >>> >>> the ida approach gives us unique id for each master,bus I would like to >>> propose using that everywhere >> >> We have cases where link2 is not used but link0, 1 and 3 are. >> Using the IDA would result in master-0,1,2 being shown, that would throw the >> integrator off. the link_id is related to hardware and can tolerate gaps, >> the IDA is typically always increasing and is across the system, not >> controller specific. >> >> We can debate forever but both pieces of information are useful, so my >> recommendation is to use both: >> >> snprintf(name, sizeof(name), "master-%d-%d", bus_id, bus->link_id); > > I agree we should use both, but does it really make sense for naming? We > can keep name in ida and expose the link_id as a parameter for > integrators to see in sysfs.
That would mean changing the meaning of sysfs properties:
/* * The sysfs for properties reflects the MIPI description as given * in the MIPI DisCo spec * * Base file is: * sdw-master-N * |---- revision * |---- clk_stop_modes * |---- max_clk_freq * |---- clk_freq * |---- clk_gears * |---- default_row * |---- default_col * |---- dynamic_shape * |---- err_threshold */
N is the link ID in the spec. I am not convinced we'd do the community a service by unilaterally changing what an external spec means, or add a property that's kernel-defined while the rest is supposed to come from firmware. If you want to change the spec then you can contribute feedback in MIPI circles (MIPI have a mechanism for maintainers to provide such feedback without company/employer membership requirements)
So either we add a sysfs layer that represents a controller (better in my opinion so that we can show the link/master count), or keep the existing hierarchy but expand the name with a unique ID so that Qualcomm don't get errors with duplicate sysfs link0 entries.
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