On Wed, May 26, 2021 at 03:48:30PM +0530, Manivannan Sadhasivam wrote:

On Tue, Mar 16, 2021 at 08:37:53PM +0200, Cristian Ciocaltea wrote:

quoted

On Tue, Mar 16, 2021 at 09:47:39AM +0530, Manivannan Sadhasivam wrote:

quoted

On Mon, Mar 08, 2021 at 07:18:28PM +0200, Cristian Ciocaltea wrote:

quoted

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!

quoted

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 }'.

This clock is gated in hw as per the datasheet. Again, please don't make
judgements based on the vendor code as it is not upto date with HW. I
know it is silly but that's how things are...

Indeed, a newer datasheet states the clock is gated. I fixed the patch
accordingly in v2.

quoted

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

CLK_IGNORE_UNUSED is used by the clk framework to essentially skip
gating the clocks which are turned ON by the bootloader and there is no
other driver using it. But I think you can remove this flag because
there is no reason to leave this specific clock to be ON always.

Thanks for the explanation, I kept the flag removed in v2.

Regards,
Cristi

Thanks,
Mani

quoted

quoted

Other than that, this patch looks good to me.

Thanks,
Cristi

[...]

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel