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

[Peter Delevoryas]

> On Jun 24, 2022, at 1:31 PM, Peter Delevoryas <pdel@fb.com> wrote:
> 
> 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

Arg, forgot this:

Fixes: ba2cccd64e90f34 ("aspeed: i2c: Add new mode support”)

Should I resend as v2?

Thanks,
Peter

> 
> 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
>