[PATCH] aspeed: i2c: Fix DMA len write-enable bit handling

[Peter Delevoryas <pdel@fb.com>]

I noticed i2c rx transfers were getting shortened to "1" on Zephyr. It
seems to be because the Zephyr i2c driver sets the RX DMA len with the
RX field write-enable bit set (bit 31) to avoid a read-modify-write. [1]

/* 0x1C : I2CM Master DMA Transfer Length Register   */

I think we should be checking the write-enable bits on the incoming
value, not checking the register array. I'm not sure we're even writing
the write-enable bits to the register array, actually.

[1] https://github.com/AspeedTech-BMC/zephyr/blob/db3dbcc9c52e67a47180890ac938ed380b33f91c/drivers/i2c/i2c_aspeed.c#L145-L148

Signed-off-by: Peter Delevoryas <pdel@fb.com>
---
 hw/i2c/aspeed_i2c.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
index 37ae1f2e04..c4fce7474a 100644
--- a/hw/i2c/aspeed_i2c.c
+++ b/hw/i2c/aspeed_i2c.c
@@ -644,18 +644,18 @@ static void aspeed_i2c_bus_new_write(AspeedI2CBus *bus, hwaddr offset,
                                                      RX_BUF_LEN) + 1;
         break;
     case A_I2CM_DMA_LEN:
-        w1t = ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN, RX_BUF_LEN_W1T) ||
-                   ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN, TX_BUF_LEN_W1T);
+        w1t = FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T) ||
+              FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN_W1T);
         /* If none of the w1t bits are set, just write to the reg as normal. */
         if (!w1t) {
             bus->regs[R_I2CM_DMA_LEN] = value;
             break;
         }
-        if (ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN, RX_BUF_LEN_W1T)) {
+        if (FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T)) {
             ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, RX_BUF_LEN,
                              FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN));
         }
-        if (ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN, TX_BUF_LEN_W1T)) {
+        if (FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN_W1T)) {
             ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, TX_BUF_LEN,
                              FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN));
         }
-- 
2.30.2