From: Hans Verkuil hans.verkuil@cisco.com
The TX FIFO has to be cleared if the transmit failed due to e.g. a NACK condition, otherwise the hardware will keep trying to transmit the message.
An attempt was made to do this, but it was done after the call to cec_transmit_done, which can cause a race condition since the call to cec_transmit_done can cause a new transmit to be issued, and then attempting to clear the TX FIFO will actually clear the new transmit instead of the old transmit and the new transmit simply never happens.
By clearing the FIFO before transmit_done is called this race is fixed.
Note that there is no reason to clear the FIFO if the transmit was successful, so the attempt to clear the FIFO in that case was dropped.
Signed-off-by: Hans Verkuil hans.verkuil@cisco.com --- drivers/gpu/drm/omapdrm/dss/hdmi4_cec.c | 35 ++++++++++++------------- 1 file changed, 17 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/omapdrm/dss/hdmi4_cec.c b/drivers/gpu/drm/omapdrm/dss/hdmi4_cec.c index 340383150fb9..dee66a5101b5 100644 --- a/drivers/gpu/drm/omapdrm/dss/hdmi4_cec.c +++ b/drivers/gpu/drm/omapdrm/dss/hdmi4_cec.c @@ -106,6 +106,22 @@ static void hdmi_cec_received_msg(struct hdmi_core_data *core) } }
+static bool hdmi_cec_clear_tx_fifo(struct cec_adapter *adap) +{ + struct hdmi_core_data *core = cec_get_drvdata(adap); + int retry = HDMI_CORE_CEC_RETRY; + int temp; + + REG_FLD_MOD(core->base, HDMI_CEC_DBG_3, 0x1, 7, 7); + while (retry) { + temp = hdmi_read_reg(core->base, HDMI_CEC_DBG_3); + if (FLD_GET(temp, 7, 7) == 0) + break; + retry--; + } + return retry != 0; +} + void hdmi4_cec_irq(struct hdmi_core_data *core) { u32 stat0 = hdmi_read_reg(core->base, HDMI_CEC_INT_STATUS_0); @@ -117,36 +133,19 @@ void hdmi4_cec_irq(struct hdmi_core_data *core) if (stat0 & 0x20) { cec_transmit_done(core->adap, CEC_TX_STATUS_OK, 0, 0, 0, 0); - REG_FLD_MOD(core->base, HDMI_CEC_DBG_3, 0x1, 7, 7); } else if (stat1 & 0x02) { u32 dbg3 = hdmi_read_reg(core->base, HDMI_CEC_DBG_3);
+ hdmi_cec_clear_tx_fifo(core->adap); cec_transmit_done(core->adap, CEC_TX_STATUS_NACK | CEC_TX_STATUS_MAX_RETRIES, 0, (dbg3 >> 4) & 7, 0, 0); - REG_FLD_MOD(core->base, HDMI_CEC_DBG_3, 0x1, 7, 7); } if (stat0 & 0x02) hdmi_cec_received_msg(core); }
-static bool hdmi_cec_clear_tx_fifo(struct cec_adapter *adap) -{ - struct hdmi_core_data *core = cec_get_drvdata(adap); - int retry = HDMI_CORE_CEC_RETRY; - int temp; - - REG_FLD_MOD(core->base, HDMI_CEC_DBG_3, 0x1, 7, 7); - while (retry) { - temp = hdmi_read_reg(core->base, HDMI_CEC_DBG_3); - if (FLD_GET(temp, 7, 7) == 0) - break; - retry--; - } - return retry != 0; -} - static bool hdmi_cec_clear_rx_fifo(struct cec_adapter *adap) { struct hdmi_core_data *core = cec_get_drvdata(adap);