[PATCH v3 10/13] drm: zynqmp_dp: Use AUX IRQs instead of polling

Sean Anderson
2024-04-22T18:46:20Z

Instead of polling the status register for the AUX status, just enable
the IRQs and signal a completion.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

Changes in v3:
- New

drivers/gpu/drm/xlnx/zynqmp_dp.c | 35 +++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 3ecfebf35a72..3d90533aefd7 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -285,6 +285,7 @@ struct zynqmp_dp_config {
* @next_bridge: The downstream bridge
* @config: IP core configuration from DTS
* @aux: aux channel
+ * @aux_done: Completed when we get an AUX reply or timeout
* @phy: PHY handles for DP lanes
* @num_lanes: number of enabled phy lanes
* @hpd_work: hot plug detection worker
@@ -305,6 +306,7 @@ struct zynqmp_dp {
struct drm_bridge bridge;
struct work_struct hpd_work;
struct work_struct hpd_irq_work;
+ struct completion aux_done;
struct mutex lock;

struct drm_bridge *next_bridge;
@@ -941,12 +943,15 @@ static int zynqmp_dp_aux_cmd_submit(struct zynqmp_dp *dp, u32 cmd, u16 addr,
u8 *buf, u8 bytes, u8 *reply)
{
bool is_read = (cmd & AUX_READ_BIT) ? true : false;
+ unsigned long time_left;
u32 reg, i;

reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REQUEST)
return -EBUSY;

+ reinit_completion(&dp->aux_done);
+
zynqmp_dp_write(dp, ZYNQMP_DP_AUX_ADDRESS, addr);
if (!is_read)
for (i = 0; i < bytes; i++)
@@ -961,17 +966,14 @@ static int zynqmp_dp_aux_cmd_submit(struct zynqmp_dp *dp, u32 cmd, u16 addr,
zynqmp_dp_write(dp, ZYNQMP_DP_AUX_COMMAND, reg);

/* Wait for reply to be delivered upto 2ms */
- for (i = 0; ; i++) {
- reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
- if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY)
- break;
+ time_left = wait_for_completion_timeout(&dp->aux_done,
+ msecs_to_jiffies(2));
+ if (!time_left)
+ return -ETIMEDOUT;

- if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT ||
- i == 2)
- return -ETIMEDOUT;
-
- usleep_range(1000, 1100);
- }
+ reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
+ if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT)
+ return -ETIMEDOUT;

reg = zynqmp_dp_read(dp, ZYNQMP_DP_AUX_REPLY_CODE);
if (reply)
@@ -1055,6 +1057,9 @@ static int zynqmp_dp_aux_init(struct zynqmp_dp *dp)
(w << ZYNQMP_DP_AUX_CLK_DIVIDER_AUX_FILTER_SHIFT) |
(rate / (1000 * 1000)));

+ zynqmp_dp_write(dp, ZYNQMP_DP_INT_EN, ZYNQMP_DP_INT_REPLY_RECEIVED |
+ ZYNQMP_DP_INT_REPLY_TIMEOUT);
+
dp->aux.name = "ZynqMP DP AUX";
dp->aux.dev = dp->dev;
dp->aux.drm_dev = dp->bridge.dev;
@@ -1072,6 +1077,9 @@ static int zynqmp_dp_aux_init(struct zynqmp_dp *dp)
static void zynqmp_dp_aux_cleanup(struct zynqmp_dp *dp)
{
drm_dp_aux_unregister(&dp->aux);
+
+ zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, ZYNQMP_DP_INT_REPLY_RECEIVED |
+ ZYNQMP_DP_INT_REPLY_TIMEOUT);
}

/* -----------------------------------------------------------------------------
@@ -1678,6 +1686,12 @@ static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
if (status & ZYNQMP_DP_INT_HPD_IRQ)
schedule_work(&dp->hpd_irq_work);

+ if (status & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY)
+ complete(&dp->aux_done);
+
+ if (status & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT)
+ complete(&dp->aux_done);
+
return IRQ_HANDLED;
}

@@ -1701,6 +1715,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
dp->dpsub = dpsub;
dp->status = connector_status_disconnected;
mutex_init(&dp->lock);
+ init_completion(&dp->aux_done);

INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func);
INIT_WORK(&dp->hpd_irq_work, zynqmp_dp_hpd_irq_work_func);
--
2.35.1.1320.gc452695387.dirty