linux-kernel - Re: [PATCHv3 2/5] ARM: dts: exynos: Add missing usbdrd3 suspend clk

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Message-ID: <20200314182010.GB17580@kozik-lap>
Date:   Sat, 14 Mar 2020 19:20:10 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     Linux USB Mailing List <linux-usb@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-samsung-soc@...r.kernel.org,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        "open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Felipe Balbi <balbi@...nel.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Tomasz Figa <tomasz.figa@...il.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCHv3 2/5] ARM: dts: exynos: Add missing usbdrd3 suspend clk

On Sat, Mar 14, 2020 at 07:02:33PM +0530, Anand Moon wrote:
> Hi Krzysztof,
> 
> On Wed, 11 Mar 2020 at 01:19, Anand Moon <linux.amoon@...il.com> wrote:
> >
> > Add new compatible strings for USBDRD3 for adding missing
> > suspend clk, exynos5422 usbdrd3 support two clk USBD300 and
> > SCLK_USBD300, so add missing suspemd_clk for Exynos542x DWC3 nodes.
> >
> > Signed-off-by: Anand Moon <linux.amoon@...il.com>
> 
> My assumption based on the FSYS clock source diagram below was bit wrong.
> [0] https://imgur.com/gallery/zAiBoyh
> 
> And again re-looking into the driver source code, it turn out their
> are *6 clock*
> Here is the correct mapping as per the Exynos5420 clock driver.
> 
> USB-(phy@...00000)
> |___________________CLK_SCLK_USBD300
> |___________________CLK_SCLK_USBPHY300
> 
> USB-(phy@...00000)
> |___________________CLK_SCLK_USBD301
> |___________________CLK_SCLK_USBPHY301
> 
> USB-(dwc3@...00000)
> |___________________CLK_USBD300
> USB-(dwc3@...00000)
> |___________________CLK_USBD301
> 
> Note: As per Exynos 5422 user manual, There are some more USB CLK
> configuration missing in GATE_IP_FSYS. So we could enable another dwc3 clk,
> If needed I would like too add this missing clk code and enable this
> clk for dwc3 driver.
> 
> For some reason we already use CLK_USBD300 and CLK_USBD301
> for PHY nodes, which lead to this confusion. So we need to update PHY clock
> CLK_USBD300 with CLK_SCLK_USBD300 and clock CLK_USBD301 with CLK_SCLK_USBD301.
> 
> Please share your thought on linking PHY nodes above and add new DWC3 clock
> and enable this clock.

The real clock topology of Exynos5422 is not properly reflected in the
kernel. However cleaning this up is quite big task.


Best regards,
Krzysztof