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

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

On Fri Jan 13, 2023 at 2:01 PM CET, Dmitry Baryshkov wrote:
> On Fri, 13 Jan 2023 at 14:44, Luca Weiss <luca.weiss@fairphone.com> wrote:
> >
> > 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.
>
> Quite simple: see [1]. DP_PLL is at +0x2000
>
> [1] https://android.googlesource.com/kernel/msm-extra/devicetree/+/refs/heads/android-msm-bramble-4.19-android11-qpr1/qcom/lagoon-sde-pll.dtsi#27

I still disagree from what I see.

E.g. this part of the dp_serdes init table in mainline:

static const struct qmp_phy_init_tbl qmp_v3_dp_serdes_tbl_rbr[] = {
	QMP_PHY_INIT_CFG(QSERDES_V3_COM_HSCLK_SEL, 0x0c),

With this one:
#define QSERDES_V3_COM_HSCLK_SEL                     0x13c

To write this config qmp->dp_serdes gets used which is set at:
	qmp->dp_serdes = base + offs->dp_serdes;

So if offs->dp_serdes is 0x2000, this write will go to 0x213c.

If we go back to msm-4.19 downstream the equivalent define is
#define USB3_DP_QSERDES_COM_HSCLK_SEL				0x113c

So there we are at offset 0x1000. And this define is used in
qcom,qmp-phy-init-seq which I already went to in detail in a previous
email in this thread.

>
> Anyway, having DP serdes at the space as USB3 serdes would mean that
> one would be setting USB3 PLL when trying to enable DP. So I could
> have said even w/o looking at the dtsi that dp serdes can _not_ be at
> 0x1000.

I don't know enough about these PHY/DP/etc blocks to say anything there.

>
> >
> > 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.
>
> Unfortunately, I don't have a recipe to test this.

No worries :)

Regards
Luca

>
> >
> > [0] https://lore.kernel.org/linux-arm-msm/CPDIYQ3SSY3E.I0Y0NMIED0WO@otso/
> >
> > Regards
> > Luca
>
>
> -- 
> With best wishes
> Dmitry