linux-kernel - Re: [PATCH v18 1/4] drm/msm/dp: do not initialize phy until plugin interrupt received

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Date:   Tue, 18 Jan 2022 15:48:42 -0600
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
        airlied@...ux.ie, bjorn.andersson@...aro.org, daniel@...ll.ch,
        dmitry.baryshkov@...aro.org, dri-devel@...ts.freedesktop.org,
        robdclark@...il.com, sean@...rly.run, vkoul@...nel.org
Cc:     quic_abhinavk@...cinc.com, aravindh@...eaurora.org,
        quic_sbillaka@...cinc.com, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v18 1/4] drm/msm/dp: do not initialize phy until plugin
 interrupt received

Quoting Kuogee Hsieh (2022-01-18 10:47:25)
> Current DP drivers have regulators, clocks, irq and phy are grouped
> together within a function and executed not in a symmetric manner.
> This increase difficulty of code maintenance and limited code scalability.
> This patch divides the driver life cycle of operation into four states,
> resume (including booting up), dongle plugin, dongle unplugged and suspend.
> Regulators, core clocks and irq are grouped together and enabled at resume
> (or booting up) so that the DP controller is armed and ready to receive HPD
> plugin interrupts. HPD plugin interrupt is generated when a dongle plugs
> into DUT (device under test). Once HPD plugin interrupt is received, DP
> controller will initialize phy so that dpcd read/write will function and
> following link training can be proceeded successfully. DP phy will be
> disabled after main link is teared down at end of unplugged HPD interrupt
> handle triggered by dongle unplugged out of DUT. Finally regulators, code
> clocks and irq are disabled at corresponding suspension.
>
> Changes in V2:
> -- removed unnecessary dp_ctrl NULL check
> -- removed unnecessary phy init_count and power_count DRM_DEBUG_DP logs
> -- remove flip parameter out of dp_ctrl_irq_enable()
> -- add fixes tag
>
> Changes in V3:
> -- call dp_display_host_phy_init() instead of dp_ctrl_phy_init() at
>         dp_display_host_init() for eDP
>
> Changes in V4:
> -- rewording commit text to match this commit changes
>
> Changes in V5:
> -- rebase on top of msm-next branch
>
> Changes in V6:
> -- delete flip variable
>
> Changes in V7:
> -- dp_ctrl_irq_enable/disabe() merged into dp_ctrl_reset_irq_ctrl()
>
> Changes in V8:
> -- add more detail comment regrading dp phy at dp_display_host_init()
>
> Changes in V9:
> -- remove set phy_initialized to false when -ECONNRESET detected
>
> Changes in v10:
> --  group into one series
>
> Changes in v11:
> -- drop drm/msm/dp: dp_link_parse_sink_count() return immediately
>         if aux read
>
> Changes in v12:
> -- move dp_display_host_phy_exit() after dp_display_host_deinit()
>
> Changes in v13:
> -- do not execute phy_init until plugged_in interrupt for edp, same as DP.
>
> Changes in v14:
> -- remove redundant dp->core_initialized = false form dp_pm_suspend.
>
> Changes in v15:
> -- remove core_initialized flag check at both host_init and host_deinit
>
> Changes in v16:
> -- remove dp_display_host_phy_exit core_initialized=false at dp_pm_suspend
>
> Changes in v17:
> -- remove core_initialized checking before execute attention_cb()
>
> Changes in v18:
> -- remove core_initialized checking at dp_pm_suspend
>
> Fixes: 8ede2ecc3e5e ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>