linux-kernel - Re: [RFT PATCH v2 02/10] drivers: qcom: rpmh-rsc: Document the register layout better

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Message-ID: <CAD=FV=XfLsvFbhAb4iEnb4zj8U_LK7zzerAz-NH6R1TQNig_tw@mail.gmail.com>
Date:   Thu, 2 Apr 2020 13:15:33 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Maulik Shah <mkshah@...eaurora.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Evan Green <evgreen@...omium.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFT PATCH v2 02/10] drivers: qcom: rpmh-rsc: Document the
 register layout better

Hi,

On Wed, Apr 1, 2020 at 1:14 AM Maulik Shah <mkshah@...eaurora.org> wrote:
>
> > + * - The first TCS block is special in that it has registers to control
> > + *   interrupts (RSC_DRV_IRQ_XXX).  Space for these registers is reserved
> > + *   in all TCS blocks to make the math easier, but only the first one
> > + *   matters.
>
> First TCS block is not special, the RSC_DRV_IRQ_XXX registers are common
> for all

Ah.  I think I see it now.  It's much easier to talk about this with
my old struct definition.  Right now I have it documented as:

/* 0x2a0 = 672 bytes big (see RSC_DRV_TCS_OFFSET) */
struct tcs_hw {
  u32 irq_enable;
  u32 irq_status;
  u32 irq_clear;
  char opaque_00c[0x4];
  u32 cmd_wait_for_cmpl;
  u32 control;
  u32 status;
  u32 cmd_enable;
  char opaque_020[0x10];
  struct tcs_cmd_hw tcs_cmd_hw[MAX_CMDS_PER_TCS];
  char opaque_170[0x130];
};

...but you're saying that it's actually:

/* 0x2a0 = 672 bytes big (see RSC_DRV_TCS_OFFSET) */
struct tcs_hw {
  u32 cmd_wait_for_cmpl;
  u32 control;
  u32 status;
  u32 cmd_enable;
  char opaque_010[0x10];
  struct tcs_cmd_hw tcs_cmd_hw[MAX_CMDS_PER_TCS];
  char opaque_160[0x140];
};

So it's still 672 bytes big but the extra "opaque" at the end is where
those bytes go.  Then, before the first TCS, there's actually 0x10
bytes of IRQ stuff.  OK, I will adjust the diagrams.

-Doug