Re: [PATCH v3 2/3] phy: qcom-qmp-combo: Add config for SM6350

["Luca Weiss" <luca.weiss@fairphone.com>]

Hi Dmitry,

On Thu Jan 12, 2023 at 8:33 PM CET, Dmitry Baryshkov wrote:
> On 12/01/2023 19:50, Vinod Koul wrote:
> > On 28-12-22, 15:17, Johan Hovold wrote:
> >> Luca, Vinod,
> >>
> >> On Wed, Nov 30, 2022 at 09:14:28AM +0100, Luca Weiss wrote:
> >>> Add the tables and config for the combo phy found on SM6350.
> >>>
> >>> Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
> >>> ---
> >>> Changes since v2:
> >>> * Drop dp_txa/dp_txb changes, not required
> >>> * Fix dp_dp_phy offset
> >>>
> >>>   drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 126 ++++++++++++++++++++++
> >>>   1 file changed, 126 insertions(+)
> >>>
> >>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> >>> index 77052c66cf70..6ac0c68269dc 100644
> >>> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> >>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> >>
> >>> @@ -975,6 +1039,19 @@ static const char * const sc7180_usb3phy_reset_l[] = {
> >>>   	"phy",
> >>>   };
> >>>   
> >>> +static const struct qmp_combo_offsets qmp_combo_offsets_v3 = {
> >>> +	.com		= 0x0000,
> >>> +	.txa		= 0x1200,
> >>> +	.rxa		= 0x1400,
> >>> +	.txb		= 0x1600,
> >>> +	.rxb		= 0x1800,
> >>> +	.usb3_serdes	= 0x1000,
> >>> +	.usb3_pcs_misc	= 0x1a00,
> >>> +	.usb3_pcs	= 0x1c00,
> >>> +	.dp_serdes	= 0x1000,
> >>
> >> I would have expected this to be 0x2000 as that's what the older
> >> platforms have been using for the dp serdes table so far. Without access
> >> to any documentation it's hard to tell whether everyone's just been
> >> cargo-culting all along or if there's actually something there at offset
> >> 0x2000.
>
> usb3_serdes is 0x1000, so dp_serdes equal to 0x1000 is definitely an typo.
>
> Judging from the downstream dtsi, the DP PHY starts at offset 0x2000. So 
> dp_serdes is equal to 0x2000, dp_phy = 0x2a00, ln_tx1 = 0x2200, ln_tx2 = 
> 0x2600.

Can you share how you got to the 0x2000 offset? You can see my
(potentially wrong) reasoning for 0x1000 a few messages ago[0].

The only 0x2000-something I could find now while looking at it again is
"#define USB3_DP_PHY_DP_DP_PHY_PD_CTL 0x2a18" which becomes
USB3_DP_DP_PHY_PD_CTL in the driver but this is seemingly not used at
all in my msm-4.19 tree.

Also if you have any idea on how to test it at runtime without actually
having to get all the type-C functionality up I'd be happy to try that.
Unfortunately I believe there's still quite some bits missing to
actually get DP out via the USB-C port - which I imagine would trigger
the PHY setup.

[0] https://lore.kernel.org/linux-arm-msm/CPDIYQ3SSY3E.I0Y0NMIED0WO@otso/

Regards
Luca

>
> >>
> >> Vinod, could you shed some light on this as presumably you have access
> >> to some documentation?
> >>
> >>> +	.dp_dp_phy	= 0x2a00,
> > 
> > No sorry, I dont have access to this version...
> > 
>
> -- 
> With best wishes
> Dmitry