sysclk-lwla: Skip unused registers in status poll

Reduce the number of long registers read in bulk during status
polling from 10 to 5. The LWLA1034 driver used to do that already
in an earlier iteration, which was then changed to be more like
the original vendor software. The reason for bringing it back now
is that it reduces the response size to 40 bytes, which works
around the spurious 64 byte limit bug in the FX2 firmware of the
LWLA devices.

diff --git a/src/hardware/sysclk-lwla/lwla1034.c b/src/hardware/sysclk-lwla/lwla1034.c
index baf3d1e94b2621733cc99395c08a62dea51283b8..fdb54e620742d061a26fbf2f625585044f85157c 100644 (file)
--- a/src/hardware/sysclk-lwla/lwla1034.c
+++ b/src/hardware/sysclk-lwla/lwla1034.c
@@ -56,9 +56,17 @@
  */
 #define READ_CHUNK_LEN36       (28 * 8)
 
-/* Bit mask for the RLE repeat-count-follows flag. */
+/* Bit mask for the RLE repeat-count-follows flag.
+ */
 #define RLE_FLAG_LEN_FOLLOWS   (UINT64_C(1) << 35)
 
+/* Start index and count for bulk long register reads.
+ * The first five long registers do not return useful values when read,
+ * so skip over them to reduce the transfer size of status poll responses.
+ */
+#define READ_LREGS_START       LREG_MEM_FILL
+#define READ_LREGS_COUNT       (LREG_STATUS + 1 - READ_LREGS_START)
+
 /** LWLA1034 register addresses.
  */
 enum reg_addr {
@@ -185,8 +193,8 @@ static inline uint64_t bulk_long_get(const struct acquisition_state *acq,
 {
        uint64_t low, high;
 
-       low  = LWLA_TO_UINT32(acq->xfer_buf_in[2 * idx]);
-       high = LWLA_TO_UINT32(acq->xfer_buf_in[2 * idx + 1]);
+       low  = LWLA_TO_UINT32(acq->xfer_buf_in[2 * (idx - READ_LREGS_START)]);
+       high = LWLA_TO_UINT32(acq->xfer_buf_in[2 * (idx - READ_LREGS_START) + 1]);
 
        return (high << 32) | low;
 }
@@ -423,8 +431,8 @@ static int prepare_request(const struct sr_dev_inst *sdi)
                break;
        case STATE_STATUS_REQUEST:
                acq->xfer_buf_out[0] = LWLA_WORD(CMD_READ_LREGS);
-               acq->xfer_buf_out[1] = LWLA_WORD(0);
-               acq->xfer_buf_out[2] = LWLA_WORD(LREG_STATUS + 1);
+               acq->xfer_buf_out[1] = LWLA_WORD(READ_LREGS_START);
+               acq->xfer_buf_out[2] = LWLA_WORD(READ_LREGS_COUNT);
                acq->xfer_out->length = 3 * sizeof(acq->xfer_buf_out[0]);
                break;
        case STATE_LENGTH_REQUEST:
@@ -463,9 +471,9 @@ static int handle_response(const struct sr_dev_inst *sdi)
 
        switch (devc->state) {
        case STATE_STATUS_REQUEST:
-               if (acq->xfer_in->actual_length != (LREG_STATUS + 1) * 8) {
+               if (acq->xfer_in->actual_length != READ_LREGS_COUNT * 8) {
                        sr_err("Received size %d doesn't match expected size %d.",
-                              acq->xfer_in->actual_length, (LREG_STATUS + 1) * 8);
+                              acq->xfer_in->actual_length, READ_LREGS_COUNT * 8);
                        return SR_ERR;
                }
                acq->mem_addr_fill = bulk_long_get(acq, LREG_MEM_FILL) & 0xFFFFFFFF;