From: Anand Moon <linux.amoon@gmail.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>,
Vinod Koul <vkoul@kernel.org>,
Neil Armstrong <narmstrong@baylibre.com>,
Kevin Hilman <khilman@baylibre.com>,
Jerome Brunet <jbrunet@baylibre.com>,
Philipp Zabel <p.zabel@pengutronix.de>,
linux-phy@lists.infradead.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-amlogic@lists.infradead.org,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFCv1 2/8] phy: amlogic: meson8b-usb2: Use phy init callback function
Date: Fri, 18 Jun 2021 18:47:03 +0530 [thread overview]
Message-ID: <CANAwSgQ=LydfoWSAo-YPOBNHu_mwOMj+6dv0pm11k-ErGAsJ2w@mail.gmail.com> (raw)
In-Reply-To: <CAFBinCAZn13-GpMw-b4=rd9zwwNCtvmv0Oq0BXt+1PTTQ+Gngw@mail.gmail.com>
Hi Martin,
On Fri, 18 Jun 2021 at 17:56, Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> Hi Anand,
>
> On Thu, Jun 17, 2021 at 9:43 PM Anand Moon <linux.amoon@gmail.com> wrote:
> >
> > Reorder the code for bulk clk_enable into .init callback function.
> Depending on whether changes are made to the dwc2 driver this is
> either fine or might cause some issues.
> My understanding is that drivers which are using a PHY should use the
> following code-flow:
> - phy_init
> - phy_power_on
> - phy_power_off
> - phy_exit
>
> dwc2's platform.c [0] however currently uses the following order:
> - phy_init
> - phy_power_on
> - (remaining ones omitted to keep this example short)
>
> So with this patch and the way dwc2 is currently implemented the
> phy_meson8b_usb2_power_on implementation might not work anymore.
> That is because the clocks are turned off and in this case all
> registers will read 0.
> You might be lucky that u-boot left the clocks enabled for your case -
> but in general I would not rely on this.
>
> In case of the phy-meson-gxl-usb2 PHY driver the ordering is different
> in the "consumer" driver (dwc3-meson-g12a.c).
> There the order is:
> - phy_init
> - phy_power_on
> - (remaining ones omitted to keep this example short)
>
> I don't know if the order in the dwc2 driver can be changed easily
> (without breaking other platforms).
> Until that dwc2 driver issue is resolved I suggest not applying this
> patch (even though in general I like the approach).
> The same thing also applies for patch #3 from this series (for
> implementing phy_ops.exit)
>
>
> Best regards,
> Martin
>
>
> [0] https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc2/platform.c#L157
Ok got your point of view.
Thanks for your review comments.
Thanks
-Anand
next prev parent reply other threads:[~2021-06-18 13:17 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 19:41 [RFCv1 0/8] Meson-8b and Meson-gxbb USB phy code re-structure Anand Moon
2021-06-17 19:41 ` [RFCv1 1/8] phy: amlogic: meson8b-usb2: Use clock bulk to get clocks for phy Anand Moon
2021-06-17 22:33 ` Martin Blumenstingl
2021-06-18 15:32 ` Anand Moon
2021-06-17 19:41 ` [RFCv1 2/8] phy: amlogic: meson8b-usb2: Use phy init callback function Anand Moon
2021-06-18 12:26 ` Martin Blumenstingl
2021-06-18 13:17 ` Anand Moon [this message]
2021-06-17 19:41 ` [RFCv1 3/8] phy: amlogic: meson8b-usb2: Use phy exit " Anand Moon
2021-06-17 19:41 ` [RFCv1 4/8] phy: amlogic: meson8b-usb2: Use phy set_mode " Anand Moon
2021-06-17 22:16 ` Martin Blumenstingl
2021-06-18 13:19 ` Anand Moon
2021-06-18 20:01 ` Martin Blumenstingl
2021-06-21 7:20 ` Anand Moon
2021-06-22 20:27 ` Martin Blumenstingl
2021-06-17 19:41 ` [RFCv1 5/8] phy: amlogic: meson8b-usb2: Reorder phy poweroff " Anand Moon
2021-06-17 22:16 ` Martin Blumenstingl
2021-06-18 15:33 ` Anand Moon
2021-06-17 19:41 ` [RFCv1 6/8] phy: amlogic: meson8b-usb2: Use phy reset " Anand Moon
2021-06-17 22:24 ` Martin Blumenstingl
2021-06-18 15:33 ` Anand Moon
2021-06-18 20:06 ` Martin Blumenstingl
2021-06-21 7:15 ` Anand Moon
2021-06-22 20:11 ` Martin Blumenstingl
2021-06-24 14:54 ` Anand Moon
2021-06-27 20:07 ` Anand Moon
2021-06-27 20:25 ` Martin Blumenstingl
2021-07-02 19:13 ` Anand Moon
2021-06-17 19:41 ` [RFCv1 7/8] phy: amlogic: meson8b-usb2: Power off the PHY by putting it into reset mode Anand Moon
2021-06-17 22:37 ` Martin Blumenstingl
2021-06-21 7:15 ` Anand Moon
2021-06-22 20:00 ` Martin Blumenstingl
2021-06-17 19:41 ` [RFCv1 8/8] phy: amlogic: meson8b-usb2: don't log an error on -EPROBE_DEFER Anand Moon
2021-06-17 22:26 ` Martin Blumenstingl
2021-06-17 22:11 ` [RFCv1 0/8] Meson-8b and Meson-gxbb USB phy code re-structure Martin Blumenstingl
2021-06-18 13:20 ` Anand Moon
2021-06-18 20:16 ` Martin Blumenstingl
2021-06-21 7:21 ` Anand Moon
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