• Kuogee Hsieh's avatar
    drm/msm/dp: do not complete dp_aux_cmd_fifo_tx() if irq is not for aux transfer · 1cba0d15
    Kuogee Hsieh authored
    There are 3 possible interrupt sources are handled by DP controller,
    HPDstatus, Controller state changes and Aux read/write transaction.
    At every irq, DP controller have to check isr status of every interrupt
    sources and service the interrupt if its isr status bits shows interrupts
    are pending. There is potential race condition may happen at current aux
    isr handler implementation since it is always complete dp_aux_cmd_fifo_tx()
    even irq is not for aux read or write transaction. This may cause aux read
    transaction return premature if host aux data read is in the middle of
    waiting for sink to complete transferring data to host while irq happen.
    This will cause host's receiving buffer contains unexpected data. This
    patch fixes this problem by checking aux isr and return immediately at
    aux isr handler if there are no any isr status bits set.
    
    Current there is a bug report regrading eDP edid corruption happen during
    system booting up. After lengthy debugging to found that VIDEO_READY
    interrupt was continuously firing during system booting up which cause
    dp_aux_isr() to complete dp_aux_cmd_fifo_tx() prematurely to retrieve data
    from aux hardware buffer which is not yet contains complete data transfer
    from sink. This cause edid corruption.
    
    Follows are the signature at kernel logs when problem happen,
    EDID has corrupt header
    panel-simple-dp-aux aux-aea0000.edp: Couldn't identify panel via EDID
    
    Changes in v2:
    -- do complete if (ret == IRQ_HANDLED) ay dp-aux_isr()
    -- add more commit text
    
    Changes in v3:
    -- add Stephen suggested
    -- dp_aux_isr() return IRQ_XXX back to caller
    -- dp_ctrl_isr() return IRQ_XXX back to caller
    
    Changes in v4:
    -- split into two patches
    
    Changes in v5:
    -- delete empty line between tags
    
    Changes in v6:
    -- remove extra "that" and fixed line more than 75 char at commit text
    
    Fixes: c943b494 ("drm/msm/dp: add displayPort driver support")
    Signed-off-by: default avatarKuogee Hsieh <quic_khsieh@quicinc.com>
    Tested-by: default avatarDouglas Anderson <dianders@chromium.org>
    Reviewed-by: default avatarAbhinav Kumar <quic_abhinavk@quicinc.com>
    Reviewed-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
    Patchwork: https://patchwork.freedesktop.org/patch/516121/
    Link: https://lore.kernel.org/r/1672193785-11003-2-git-send-email-quic_khsieh@quicinc.comSigned-off-by: default avatarAbhinav Kumar <quic_abhinavk@quicinc.com>
    1cba0d15
dp_aux.c 12.7 KB