Re: [PATCH v3 2/3] hw/i2c/aspeed: Fix TXBUF transmission start position error

[Cédric Le Goater]

On 8/12/23 08:52, Hang Yu wrote:

According to the ast2600 datasheet and the linux aspeed i2c driver,
the TXBUF transmission start position should be TXBUF[0] instead
of TXBUF[1],so the arg pool_start is useless,and the address is not
included in TXBUF.So even if Tx Count equals zero,there is at least
1 byte data needs to be transmitted,and M_TX_CMD should not be cleared
at this condition.The driver url is:
https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v5.15/drivers/i2c/busses/i2c-ast2600.c

Signed-off-by: Hang Yu <francis_...@stu.pku.edu.cn>

This is -stable material with the previous patch. It fixes support for
the v08.06 SDK.

Fixes: 6054fc73e8f4 ("aspeed/i2c: Add support for pool buffer transfers")

Reviewed-by: Cédric Le Goater <c...@kaod.org>

Thanks,

C.

---
v2-->v3:
No change.

  hw/i2c/aspeed_i2c.c | 30 ++++++------------------------
  1 file changed, 6 insertions(+), 24 deletions(-)

diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
index e485d8bfb8..44905d7899 100644
--- a/hw/i2c/aspeed_i2c.c
+++ b/hw/i2c/aspeed_i2c.c
@@ -226,7 +226,7 @@ static int aspeed_i2c_dma_read(AspeedI2CBus *bus, uint8_t 
*data)
      return 0;
  }

-static int aspeed_i2c_bus_send(AspeedI2CBus *bus, uint8_t pool_start)

+static int aspeed_i2c_bus_send(AspeedI2CBus *bus)
  {
      AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
      int ret = -1;
@@ -239,7 +239,7 @@ static int aspeed_i2c_bus_send(AspeedI2CBus *bus, uint8_t 
pool_start)
                                                  TX_COUNT) + 1;

if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {

-        for (i = pool_start; i < pool_tx_count; i++) {
+        for (i = 0; i < pool_tx_count; i++) {
              uint8_t *pool_base = aic->bus_pool_base(bus);

trace_aspeed_i2c_bus_send("BUF", i + 1, pool_tx_count,

@@ -273,7 +273,7 @@ static int aspeed_i2c_bus_send(AspeedI2CBus *bus, uint8_t 
pool_start)
          }
          SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, TX_DMA_EN, 0);
      } else {
-        trace_aspeed_i2c_bus_send("BYTE", pool_start, 1,
+        trace_aspeed_i2c_bus_send("BYTE", 0, 1,
                                    bus->regs[reg_byte_buf]);
          ret = i2c_send(bus->bus, bus->regs[reg_byte_buf]);
      }
@@ -446,10 +446,8 @@ static void aspeed_i2c_bus_cmd_dump(AspeedI2CBus *bus)
   */
  static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, uint64_t value)
  {
-    uint8_t pool_start = 0;
      uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
      uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
-    uint32_t reg_pool_ctrl = aspeed_i2c_bus_pool_ctrl_offset(bus);
      uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);

if (!aspeed_i2c_check_sram(bus)) {

@@ -483,27 +481,11 @@ static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, 
uint64_t value)

SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_START_CMD, 0); - /*

-         * The START command is also a TX command, as the slave
-         * address is sent on the bus. Drop the TX flag if nothing
-         * else needs to be sent in this sequence.
-         */
-        if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {
-            if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_pool_ctrl, TX_COUNT)
-                == 0) {
-                SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
-            } else {
-                /*
-                 * Increase the start index in the TX pool buffer to
-                 * skip the address byte.
-                 */
-                pool_start++;
-            }
-        } else if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)) {
+        if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)) {
              if (bus->regs[reg_dma_len] == 0) {
                  SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
              }
-        } else {
+        } else if (!SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {
              SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
          }

@@ -520,7 +502,7 @@ static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, uint64_t value) if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_TX_CMD)) {

          aspeed_i2c_set_state(bus, I2CD_MTXD);
-        if (aspeed_i2c_bus_send(bus, pool_start)) {
+        if (aspeed_i2c_bus_send(bus)) {
              SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, TX_NAK, 1);
              i2c_end_transfer(bus->bus);
          } else {