Messages in this thread | | | Date | Mon, 19 Sep 2022 09:11:10 +0200 | From | Tommaso Merciai <> | Subject | Re: [PATCH v2 2/2] media: i2c: add support for ov4689 |
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Hi Sakari,
On Mon, Sep 19, 2022 at 06:33:12AM +0000, Sakari Ailus wrote: > Hi Tommaso, > > On Fri, Sep 16, 2022 at 03:34:01PM +0200, Tommaso Merciai wrote: > > > >> + ret = clk_set_rate(ov4689->xvclk, OV4689_XVCLK_FREQ); > > > >> + if (ret < 0) { > > > >> + dev_err(dev, "Failed to set xvclk rate (24MHz)\n"); > > > >> + return ret; > > > >> + } > > > >> + if (clk_get_rate(ov4689->xvclk) != OV4689_XVCLK_FREQ) > > > >> + dev_warn(dev, "xvclk mismatched, modes are based on 24MHz\n"); > > > > > > > > > > > > What do you think about? > > > > Thanks. > > > > > > Unfortunately, I have no experience with ACPI-based devices. :( > > > > > > Do you mean that in the case of an ACPI device and devm_clk_get_optional > > > returning NULL we should assume that the clock is already enabled and > > > will stay enabled during sensor operation? How should we distinguish it > > > from the case of an OF-based system and clock just missing from device > > > tree? > > > > Not exaclty :) > > > > I copy comment from [1] > > > > if you use ov5693->xvclk to identify the ACPI vs OF use case shouldn't > > you use the get_optionl() version ? Otherwise in the ACPI case you will have > > -ENOENT if there's not 'xvclk' property and bail out. > > > > Unless my understanding is wrong on ACPI we have "clock-frequency" and > > on OF "xvclk" with an "assigned-clock-rates", > > Generally yes. It's also possible to have a clock in ACPI based system > although those clocks do not come from ACPI. See e.g. > drivers/platform/x86/intel/int3472/clk_and_regulator.c .
I save this :) Thanks for sharing.
Regards, Tommaso
> > -- > Sakari Ailus
-- Tommaso Merciai Embedded Linux Engineer tommaso.merciai@amarulasolutions.com __________________________________
Amarula Solutions SRL Via Le Canevare 30, 31100 Treviso, Veneto, IT T. +39 042 243 5310 info@amarulasolutions.com www.amarulasolutions.com
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