Re: [PATCH 3/6] clk: actions: Fix bisp_factor_table based clocks on Owl S500 SoC

Cristian Ciocaltea
2021-03-16T18:38:46Z

On Tue, Mar 16, 2021 at 09:47:39AM +0530, Manivannan Sadhasivam wrote:
> On Mon, Mar 08, 2021 at 07:18:28PM +0200, Cristian Ciocaltea wrote:
> > The following clocks of the Actions Semi Owl S500 SoC have been defined
> > to use a shared clock factor table 'bisp_factor_table[]': DE[1-2], VCE,
> > VDE, BISP, SENSOR[0-1]
> >
> > There are several issues involved in this approach:
> >
> > * 'bisp_factor_table[]' describes the configuration of a regular 8-rates
> > divider, so its usage is redundant. Additionally, judging by the BISP
> > clock context, it is incomplete since it maps only 8 out of 12
> > possible entries.
> >
> > * The clocks mentioned above are not identical in terms of the available
> > rates, therefore cannot rely on the same factor table. Specifically,
> > BISP and SENSOR* are standard 12-rate dividers so their configuration
> > should rely on a proper clock div table, while VCE and VDE require a
> > factor table that is a actually a subset of the one needed for DE[1-2]
> > clocks.
> >
> > Let's fix this by implementing the following:
> >
> > * Add new factor tables 'de_factor_table' and 'hde_factor_table' to
> > properly handle DE[1-2], VCE and VDE clocks.
> >
> > * Add a common div table 'std12rate_div_table' for BISP and SENSOR[0-1]
> > clocks converted to OWL_COMP_DIV.
> >
> > * Drop the now unused 'bisp_factor_table[]'.
> >
>
> Nice!
>
> > Additionally, since SENSOR[0-1] are not gated, unset the OWL_GATE_HW
> > configuration and drop the CLK_IGNORE_UNUSED flag in their definitions.
> >
>
> No. You should not screen the functionality exposed by the hw, that's what the
> purpose of these CLK_ flags.

I'm not sure I get this, or maybe I wasn't clear enough with my
explanation regarding the changes to SENSOR clocks: they are not gated
in hardware, hence the statement 'OWL_GATE_HW(CMU_DEVCLKEN0, 14, 0)'
was invalid and I replaced it with '{ 0 }'.

Additionally, I assumed the 'CLK_IGNORE_UNUSED' flag makes sense only
for the gated clocks. Do I miss something?

> Other than that, this patch looks good to me.

Thanks,
Cristi …