From: Alvin Šipraga alsi@bang-olufsen.dk

The ADV7511 family of bridges supports two modes for CEC RX: legacy and non-legacy mode. The only difference is whether the chip uses a single CEC RX buffer, or uses all three available RX buffers. Currently the adv7511 driver uses legacy mode.

While debugging a stall in CEC RX on an ADV7535, we reached out to Analog Devices, who suggested to use non-legacy mode instead. According to the programming guide for the ADV7511 [1], and the register control manual of the ADV7535 [2], this is the default behaviour on reset. As previously stated, the adv7511 driver currently overrides this to legacy mode.

This patch updates the adv7511 driver to instead use non-legacy mode with all three CEC RX buffers. As a result of this change, we no longer experience any stalling of CEC RX with the ADV7535. It is not known why non-legacy mode solves this particular issue, but besides this, no functional change is to be expected by this patch. Please note that this has only been tested on an ADV7535.

What follows is a brief description of the non-legacy mode interrupt handling behaviour. The programming guide in [1] gives a more detailed explanation.

With three RX buffers, the interrupt handler checks the CEC_RX_STATUS register (renamed from CEC_RX_ENABLE in this patch), which contains 2-bit psuedo-timestamps for each of the RX buffers. The RX timestamps for each buffer represent the time of arrival for the CEC frame held in a given buffer, with lower timestamp values indicating chronologically older frames. A special value of 0 indicates that the given RX buffer is inactive and should be skipped. The interrupt handler parses these timestamps and then reads the active RX buffers in the prescribed order using the same logic as before. Changes have been made to ensure that the correct RX buffer is cleared after processing. This clearing procesure also sets the timestamp of the given RX buffer to 0 to mark it as inactive.

[1] https://www.analog.com/media/en/technical-documentation/user-guides/ADV7511_... cf. CEC Map, register 0x4A, bit 3, default value 1: 0 = Use only buffer 0 to store CEC frames (Legacy mode) 1 = Use all 3 buffers to stores the CEC frames (Non-legacy mode)

[2] The ADV7535 register control manual is under NDA, but trust me when I say that non-legacy CEC RX mode is the default here too. Here the register is offset by 0x70 and has an address of 0xBA in the DSI_CEC regiser map.

Signed-off-by: Alvin Šipraga alsi@bang-olufsen.dk Reviewed-by: Robert Foss robert.foss@linaro.org --- drivers/gpu/drm/bridge/adv7511/adv7511.h | 26 +++++- drivers/gpu/drm/bridge/adv7511/adv7511_cec.c | 98 +++++++++++++++----- drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 14 ++- 3 files changed, 106 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h index da6d8ee2cd84..9e3bb8a8ee40 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h @@ -209,10 +209,16 @@ #define ADV7511_REG_CEC_TX_ENABLE 0x11 #define ADV7511_REG_CEC_TX_RETRY 0x12 #define ADV7511_REG_CEC_TX_LOW_DRV_CNT 0x14 -#define ADV7511_REG_CEC_RX_FRAME_HDR 0x15 -#define ADV7511_REG_CEC_RX_FRAME_DATA0 0x16 -#define ADV7511_REG_CEC_RX_FRAME_LEN 0x25 -#define ADV7511_REG_CEC_RX_ENABLE 0x26 +#define ADV7511_REG_CEC_RX1_FRAME_HDR 0x15 +#define ADV7511_REG_CEC_RX1_FRAME_DATA0 0x16 +#define ADV7511_REG_CEC_RX1_FRAME_LEN 0x25 +#define ADV7511_REG_CEC_RX_STATUS 0x26 +#define ADV7511_REG_CEC_RX2_FRAME_HDR 0x27 +#define ADV7511_REG_CEC_RX2_FRAME_DATA0 0x28 +#define ADV7511_REG_CEC_RX2_FRAME_LEN 0x37 +#define ADV7511_REG_CEC_RX3_FRAME_HDR 0x38 +#define ADV7511_REG_CEC_RX3_FRAME_DATA0 0x39 +#define ADV7511_REG_CEC_RX3_FRAME_LEN 0x48 #define ADV7511_REG_CEC_RX_BUFFERS 0x4a #define ADV7511_REG_CEC_LOG_ADDR_MASK 0x4b #define ADV7511_REG_CEC_LOG_ADDR_0_1 0x4c @@ -220,6 +226,18 @@ #define ADV7511_REG_CEC_CLK_DIV 0x4e #define ADV7511_REG_CEC_SOFT_RESET 0x50

+static const u8 ADV7511_REG_CEC_RX_FRAME_HDR[] = { + ADV7511_REG_CEC_RX1_FRAME_HDR, + ADV7511_REG_CEC_RX2_FRAME_HDR, + ADV7511_REG_CEC_RX3_FRAME_HDR, +}; + +static const u8 ADV7511_REG_CEC_RX_FRAME_LEN[] = { + ADV7511_REG_CEC_RX1_FRAME_LEN, + ADV7511_REG_CEC_RX2_FRAME_LEN, + ADV7511_REG_CEC_RX3_FRAME_LEN, +}; + #define ADV7533_REG_CEC_OFFSET 0x70

enum adv7511_input_clock { diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c index 1f619389e201..399f625a50c8 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c @@ -17,7 +17,8 @@

#define ADV7511_INT1_CEC_MASK \ (ADV7511_INT1_CEC_TX_READY | ADV7511_INT1_CEC_TX_ARBIT_LOST | \ - ADV7511_INT1_CEC_TX_RETRY_TIMEOUT | ADV7511_INT1_CEC_RX_READY1) + ADV7511_INT1_CEC_TX_RETRY_TIMEOUT | ADV7511_INT1_CEC_RX_READY1 | \ + ADV7511_INT1_CEC_RX_READY2 | ADV7511_INT1_CEC_RX_READY3)

static void adv_cec_tx_raw_status(struct adv7511 *adv7511, u8 tx_raw_status) { @@ -70,25 +71,16 @@ static void adv_cec_tx_raw_status(struct adv7511 *adv7511, u8 tx_raw_status) } }

-void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1) +static void adv7511_cec_rx(struct adv7511 *adv7511, int rx_buf) { unsigned int offset = adv7511->reg_cec_offset; - const u32 irq_tx_mask = ADV7511_INT1_CEC_TX_READY | - ADV7511_INT1_CEC_TX_ARBIT_LOST | - ADV7511_INT1_CEC_TX_RETRY_TIMEOUT; struct cec_msg msg = {}; unsigned int len; unsigned int val; u8 i;

- if (irq1 & irq_tx_mask) - adv_cec_tx_raw_status(adv7511, irq1); - - if (!(irq1 & ADV7511_INT1_CEC_RX_READY1)) - return; - if (regmap_read(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_FRAME_LEN + offset, &len)) + ADV7511_REG_CEC_RX_FRAME_LEN[rx_buf] + offset, &len)) return;

msg.len = len & 0x1f; @@ -101,18 +93,76 @@ void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1)

for (i = 0; i < msg.len; i++) { regmap_read(adv7511->regmap_cec, - i + ADV7511_REG_CEC_RX_FRAME_HDR + offset, &val); + i + ADV7511_REG_CEC_RX_FRAME_HDR[rx_buf] + offset, + &val); msg.msg[i] = val; }

- /* toggle to re-enable rx 1 */ - regmap_write(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_BUFFERS + offset, 1); - regmap_write(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_BUFFERS + offset, 0); + /* Toggle RX Ready Clear bit to re-enable this RX buffer */ + regmap_update_bits(adv7511->regmap_cec, + ADV7511_REG_CEC_RX_BUFFERS + offset, BIT(rx_buf), + BIT(rx_buf)); + regmap_update_bits(adv7511->regmap_cec, + ADV7511_REG_CEC_RX_BUFFERS + offset, BIT(rx_buf), 0); + cec_received_msg(adv7511->cec_adap, &msg); }

+void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1) +{ + unsigned int offset = adv7511->reg_cec_offset; + const u32 irq_tx_mask = ADV7511_INT1_CEC_TX_READY | + ADV7511_INT1_CEC_TX_ARBIT_LOST | + ADV7511_INT1_CEC_TX_RETRY_TIMEOUT; + const u32 irq_rx_mask = ADV7511_INT1_CEC_RX_READY1 | + ADV7511_INT1_CEC_RX_READY2 | + ADV7511_INT1_CEC_RX_READY3; + unsigned int rx_status; + int rx_order[3] = { -1, -1, -1 }; + int i; + + if (irq1 & irq_tx_mask) + adv_cec_tx_raw_status(adv7511, irq1); + + if (!(irq1 & irq_rx_mask)) + return; + + if (regmap_read(adv7511->regmap_cec, + ADV7511_REG_CEC_RX_STATUS + offset, &rx_status)) + return; + + /* + * ADV7511_REG_CEC_RX_STATUS[5:0] contains the reception order of RX + * buffers 0, 1, and 2 in bits [1:0], [3:2], and [5:4] respectively. + * The values are to be interpreted as follows: + * + * 0 = buffer unused + * 1 = buffer contains oldest received frame (if applicable) + * 2 = buffer contains second oldest received frame (if applicable) + * 3 = buffer contains third oldest received frame (if applicable) + * + * Fill rx_order with the sequence of RX buffer indices to + * read from in order, where -1 indicates that there are no + * more buffers to process. + */ + for (i = 0; i < 3; i++) { + unsigned int timestamp = (rx_status >> (2 * i)) & 0x3; + + if (timestamp) + rx_order[timestamp - 1] = i; + } + + /* Read CEC RX buffers in the appropriate order as prescribed above */ + for (i = 0; i < 3; i++) { + int rx_buf = rx_order[i]; + + if (rx_buf < 0) + break; + + adv7511_cec_rx(adv7511, rx_buf); + } +} + static int adv7511_cec_adap_enable(struct cec_adapter *adap, bool enable) { struct adv7511 *adv7511 = cec_get_drvdata(adap); @@ -126,11 +176,11 @@ static int adv7511_cec_adap_enable(struct cec_adapter *adap, bool enable) regmap_update_bits(adv7511->regmap_cec, ADV7511_REG_CEC_CLK_DIV + offset, 0x03, 0x01); - /* legacy mode and clear all rx buffers */ + /* non-legacy mode and clear all rx buffers */ regmap_write(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_BUFFERS + offset, 0x07); + ADV7511_REG_CEC_RX_BUFFERS + offset, 0x0f); regmap_write(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_BUFFERS + offset, 0); + ADV7511_REG_CEC_RX_BUFFERS + offset, 0x08); /* initially disable tx */ regmap_update_bits(adv7511->regmap_cec, ADV7511_REG_CEC_TX_ENABLE + offset, 1, 0); @@ -138,7 +188,7 @@ static int adv7511_cec_adap_enable(struct cec_adapter *adap, bool enable) /* tx: ready */ /* tx: arbitration lost */ /* tx: retry timeout */ - /* rx: ready 1 */ + /* rx: ready 1-3 */ regmap_update_bits(adv7511->regmap, ADV7511_REG_INT_ENABLE(1), 0x3f, ADV7511_INT1_CEC_MASK); @@ -304,9 +354,9 @@ int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511) regmap_write(adv7511->regmap_cec, ADV7511_REG_CEC_SOFT_RESET + offset, 0x00);

- /* legacy mode */ + /* non-legacy mode - use all three RX buffers */ regmap_write(adv7511->regmap_cec, - ADV7511_REG_CEC_RX_BUFFERS + offset, 0x00); + ADV7511_REG_CEC_RX_BUFFERS + offset, 0x08);

regmap_write(adv7511->regmap_cec, ADV7511_REG_CEC_CLK_DIV + offset, diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c index 556ba1b447ba..5bb9300040dd 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c @@ -1030,10 +1030,16 @@ static bool adv7511_cec_register_volatile(struct device *dev, unsigned int reg) reg -= adv7511->reg_cec_offset;

switch (reg) { - case ADV7511_REG_CEC_RX_FRAME_HDR: - case ADV7511_REG_CEC_RX_FRAME_DATA0... - ADV7511_REG_CEC_RX_FRAME_DATA0 + 14: - case ADV7511_REG_CEC_RX_FRAME_LEN: + case ADV7511_REG_CEC_RX1_FRAME_HDR: + case ADV7511_REG_CEC_RX1_FRAME_DATA0 ... ADV7511_REG_CEC_RX1_FRAME_DATA0 + 14: + case ADV7511_REG_CEC_RX1_FRAME_LEN: + case ADV7511_REG_CEC_RX2_FRAME_HDR: + case ADV7511_REG_CEC_RX2_FRAME_DATA0 ... ADV7511_REG_CEC_RX2_FRAME_DATA0 + 14: + case ADV7511_REG_CEC_RX2_FRAME_LEN: + case ADV7511_REG_CEC_RX3_FRAME_HDR: + case ADV7511_REG_CEC_RX3_FRAME_DATA0 ... ADV7511_REG_CEC_RX3_FRAME_DATA0 + 14: + case ADV7511_REG_CEC_RX3_FRAME_LEN: + case ADV7511_REG_CEC_RX_STATUS: case ADV7511_REG_CEC_RX_BUFFERS: case ADV7511_REG_CEC_TX_LOW_DRV_CNT: return true;