On 20-12-08 16:24:11, Ben Widawsky wrote:
[snip]
> +static int cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
> + struct mbox_cmd *mbox_cmd)
> +{
> + u64 cmd, status;
> + size_t out_len;
> + int rc;
> +
> + lockdep_assert_held(&cxlm->mbox_lock);
> +
> + /*
> + * Here are the steps from 8.2.8.4 of the CXL 2.0 spec.
> + * 1. Caller reads MB Control Register to verify doorbell is clear
> + * 2. Caller writes Command Register
> + * 3. Caller writes Command Payload Registers if input payload is
> non-empty
> + * 4. Caller writes MB Control Register to set doorbell
> + * 5. Caller either polls for doorbell to be clear or waits for
> interrupt if configured
> + * 6. Caller reads MB Status Register to fetch Return code
> + * 7. If command successful, Caller reads Command Register to get
> Payload Length
> + * 8. If output payload is non-empty, host reads Command Payload
> Registers
> + */
> +
> + /* #1 */
> + WARN_ON(cxl_doorbell_busy(cxlm));
> +
> + /* #2 */
> + cxl_write_mbox_reg64(cxlm, CXLDEV_MB_CMD_OFFSET, mbox_cmd->opcode);
> +
> + if (mbox_cmd->size_in) {
> + /* #3 */
> + CXL_SET_FIELD(mbox_cmd->size_in, CXLDEV_MB_CMD_PAYLOAD_LENGTH);
> + cxl_mbox_payload_fill(cxlm, mbox_cmd->payload,
> + mbox_cmd->size_in);
> + }
There is a bug here where the payload length isn't written on input. It was
working in v1. It will be fixed in v3.
[snip]
