linux-kernel - Re: [PATCH v4 1/2] ARM: dts: aspeed: Add KCS & lpc ctrl for Facebook

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Message-ID: <017219A7-E5A7-41B8-869C-B54FABF401A7@fb.com>
Date:   Thu, 13 Dec 2018 19:18:27 +0000
From:   Vijay Khemka <vijaykhemka@...com>
To:     Joel Stanley <joel@....id.au>, Andrew Jeffery <andrew@...id.au>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v4 1/2] ARM: dts: aspeed: Add KCS & lpc ctrl for Facebook



On 12/12/18, 5:04 PM, "Joel Stanley" <joel@....id.au> wrote:

    On Thu, 13 Dec 2018 at 07:34, Vijay Khemka <vijaykhemka@...com> wrote:
    >
    > Added kcs device and lpc ctrl device to enable LPC clock in Facebook
    > Tiogapass device tree.
    
    As we're going to re-spin, it's a good idea to have the KCS and LPC
    changes in separate patches. I will take the KCS one straight away,
    but the LPC one might need more work (see my comments below).

Thanks Joel,
I will create different patches and resubmit again.
    
    >
    > Signed-off-by: Vijay Khemka <vijaykhemka@...com>
    > ---
    >  .../dts/aspeed-bmc-facebook-tiogapass.dts     | 30 +++++++++++++++++++
    >  1 file changed, 30 insertions(+)
    >
    > diff --git a/arch/arm/boot/dts/aspeed-bmc-facebook-tiogapass.dts b/arch/arm/boot/dts/aspeed-bmc-facebook-tiogapass.dts
    > index d9d7f208788a..9544fa2c1822 100644
    > --- a/arch/arm/boot/dts/aspeed-bmc-facebook-tiogapass.dts
    > +++ b/arch/arm/boot/dts/aspeed-bmc-facebook-tiogapass.dts
    > @@ -21,6 +21,18 @@
    >         memory@...00000 {
    >                 reg = <0x80000000 0x20000000>;
    >         };
    > +
    > +       reserved-memory {
    > +               #address-cells = <1>;
    > +               #size-cells = <1>;
    > +               ranges;
    > +
    > +               flash_memory: region@...00000 {
    > +                       no-map;
    > +                       reg = <0x98000000 0x04000000>; /* 64M */
    > +               };
    
    Are you using this to expose some RAM over LPC? If not, we don't want this here.
No, we are not using currently.
    
    It is a flaw in the design of the driver that the reserved memory
    region is required. We should change the driver to make it optional.
I agree with you we should make this change in driver.
    
    As a workaround, we could add this patch to the tiogapass device tree
    but make it smaller so you're not losing 64MB of RAM.
I will make it to 4K.
    
    > +       };
    > +
    >         iio-hwmon {
    >                 compatible = "iio-hwmon";
    >                 oemname0 = "MB_P3V3";
    > @@ -62,6 +74,12 @@
    >         };
    >  };
    >
    > +&lpc_ctrl {
    > +       status = "okay";
    > +       memory-region = <&flash_memory>;
    > +       flash = <&spi1>;
    > +};
    > +
    >  &uart1 {
    >         // Host Console
    >         status = "okay";
    > @@ -75,6 +93,18 @@
    >         status = "okay";
    >  };
    >
    > +&kcs2 {
    > +       // BMC KCS channel 2
    > +       status = "okay";
    > +       kcs_addr = <0xca8>;
    > +};
    > +
    > +&kcs3 {
    > +       // BMC KCS channel 3
    > +       status = "okay";
    > +       kcs_addr = <0xca2>;
    > +};
    > +
    >  &mac0 {
    >         status = "okay";
    >
    > --
    > 2.17.1
    >