Re: [PATCH 02/14] dt-bindings: phy: qcom,qmp-usb3-dp: fix sc8280xp bindings

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On 14/11/2022 19:42, Johan Hovold wrote:
On Mon, Nov 14, 2022 at 07:14:48PM +0300, Dmitry Baryshkov wrote:
On 14/11/2022 18:38, Johan Hovold wrote:
On Mon, Nov 14, 2022 at 06:19:25PM +0300, Dmitry Baryshkov wrote:
On 14/11/2022 17:18, Johan Hovold wrote:
On Mon, Nov 14, 2022 at 03:07:41PM +0100, Krzysztof Kozlowski wrote:
On 14/11/2022 14:27, Johan Hovold wrote:
On Fri, Nov 11, 2022 at 04:17:29PM +0100, Krzysztof Kozlowski wrote:
On 11/11/2022 10:24, Johan Hovold wrote:

I noticed that several bindings leave the clock indexes unspecified, or
have header files defining some or all of them. I first added a QMP
header but that seemed like overkill, especially if we'd end up with
one header per SoC (cf. the GCC headers) due to (known and potential)
platform differences.

Shall I add back a shared header for all PHYs handled by this driver
(another implementation detail) even if this could eventually lead to
describing clocks not supported by a particular SoC (so such constraints
would still need to be described by the binding somehow):

	/* QMP clocks */
	#define QMP_USB3_PIPE_CLK	0
	#define QMP_DP_LINK_CLK		1
	#define QMP_DP_VCO_DIV_CLK	2

Maybe QMP_COMBO_USB3_PIPE_CLK, QMP_COMBO_DP_LINK_CLK,
QMP_COMBO_DP_VCO_DIV_CLK?

"COMBO" is just the name of the Linux driver and does not belong in the
binding.

We do not have any standard (iow, coming from the docs) name, so we can
invent it on our own.

I still think the naming should reflect the hardware and not the Linux
implementation if this is going into the binding.

Well, I always viewed docs as


And the USB4_USB3_DP defines are going to be a superset of USB3_DP (as
far we know know).

I'll then extend this header with QMP_UFS_RX_SYMBOL_0_CLK
QMP_UFS_RX_SYMBOL_1_CLK and QMP_UFS_TX_SYMBOL_0_CLK.

Yeah, I had those in mind when creating the header and using a generic
QMP prefix (even if I didn't end up using the header in v1).

This could just be mapping of (arbitrary) QMP indexes to clocks and we
use it for USB3, DP, UFS and later also USB4.

This will however mean that the indexes are not necessarily zero-based
and consecutive for a specific SoC and PHY. But that's perhaps a
non-issue (cf. the PHY_TYPE defines).

Ugh. Please, no. We have symbol clocks for UFS PHY, USB+DP clocks for
USB+DP PHY, but let's not go for the unified clocks index definition.

Yeah, this is the kind of issues I wanted to avoid by not using a per
SoC header for three clocks which will almost always use the same
indexes.

Because how can you be sure that your unified per-PHY type defines will
never have to be amended? Or some index left out?

The only way then is to have per-SoC defines which is a pain to
maintain (just consider that driver mapping table when some odd SoC
shows up).

My vote is definitely against a per-SoC defines.


Johan

--
With best wishes
Dmitry




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