This is an automated email from Gerrit.
"Tomas Vanek <van...@fbl.cz>" just uploaded a new patch set to Gerrit, which
you can find at https://review.openocd.org/c/openocd/+/7218
-- gerrit
commit 660576fd51f5dd9d57e46a79462a1fbeafb90e5f
Author: Tomas Vanek <van...@fbl.cz>
Date: Wed Sep 21 14:26:07 2022 +0200
target/adi_v5_swd: optimize sequences in swd_connect_multidrop()
swd_connect_multidrop() sent DORMANT_TO_SWD and called
swd_multidrop_select_inner(). DORMANT_TO_SWD sequence ends
with a LINE_RESET sequence.
swd_multidrop_select_inner() sent LINE_RESET sequence again.
It was useless in this case.
Move LINE_RESET sending to swd_multidrop_select().
swd_connect_multidrop() now sends just one LINE_RESET
(the one contained in DORMANT_TO_SWD).
Change-Id: Iba21620f6a9680793208bf398960ed0eb59df3b1
Signed-off-by: Tomas Vanek <van...@fbl.cz>
diff --git a/src/target/adi_v5_swd.c b/src/target/adi_v5_swd.c
index aea730d4d1..c948852977 100644
--- a/src/target/adi_v5_swd.c
+++ b/src/target/adi_v5_swd.c
@@ -176,21 +176,6 @@ static int swd_multidrop_select_inner(struct adiv5_dap
*dap, uint32_t *dpidr_ptr
assert(dap_is_multidrop(dap));
- swd_send_sequence(dap, LINE_RESET);
- /* From ARM IHI 0074C ADIv6.0, chapter B4.3.3 "Connection and line reset
- * sequence":
- * - line reset sets DP_SELECT_DPBANK to zero;
- * - read of DP_DPIDR takes the connection out of reset;
- * - write of DP_TARGETSEL keeps the connection in reset;
- * - other accesses return protocol error (SWDIO not driven by target).
- *
- * Read DP_DPIDR to get out of reset. Initialize dap->select to zero to
- * skip the write to DP_SELECT, avoiding the protocol error. Set again
- * dap->select to DP_SELECT_INVALID because the rest of the register is
- * unknown after line reset.
- */
- dap->select = 0;
-
retval = swd_queue_dp_write_inner(dap, DP_TARGETSEL,
dap->multidrop_targetsel);
if (retval != ERROR_OK)
return retval;
@@ -209,6 +194,9 @@ static int swd_multidrop_select_inner(struct adiv5_dap
*dap, uint32_t *dpidr_ptr
return retval;
}
+ /* Set dap->select to DP_SELECT_INVALID because all field of the
register
+ * except DPBANKSEL are unknown after line reset.
+ */
dap->select = DP_SELECT_INVALID;
retval = swd_queue_dp_read_inner(dap, DP_DLPIDR, &dlpidr);
@@ -260,6 +248,19 @@ static int swd_multidrop_select(struct adiv5_dap *dap)
for (unsigned int retry = 0; ; retry++) {
bool clear_sticky = retry > 0;
+ swd_send_sequence(dap, LINE_RESET);
+ /* From ARM IHI 0074C ADIv6.0, chapter B4.3.3 "Connection and
line reset
+ * sequence":
+ * - line reset sets DP_SELECT_DPBANK to zero;
+ * - read of DP_DPIDR takes the connection out of reset;
+ * - write of DP_TARGETSEL keeps the connection in reset;
+ * - other accesses return protocol error (SWDIO not driven by
target).
+ *
+ * Read DP_DPIDR to get out of reset. Initialize dap->select to
zero to
+ * skip the write to DP_SELECT, avoiding the protocol error.
+ */
+ dap->select = 0;
+
retval = swd_multidrop_select_inner(dap, NULL, NULL,
clear_sticky);
if (retval == ERROR_OK)
break;
@@ -295,6 +296,19 @@ static int swd_connect_multidrop(struct adiv5_dap *dap)
dap_invalidate_cache(dap);
swd_multidrop_selected_dap = NULL;
+ /* The sequence DORMANT_TO_SWD ends with a SWD line reset
sequence.
+ * From ARM IHI 0074C ADIv6.0, chapter B4.3.3 "Connection and
line reset
+ * sequence":
+ * - line reset sets DP_SELECT_DPBANK to zero;
+ * - read of DP_DPIDR takes the connection out of reset;
+ * - write of DP_TARGETSEL keeps the connection in reset;
+ * - other accesses return protocol error (SWDIO not driven by
target).
+ *
+ * Read DP_DPIDR to get out of reset. Initialize dap->select to
zero to
+ * skip the write to DP_SELECT, avoiding the protocol error.
+ */
+ dap->select = 0;
+
retval = swd_multidrop_select_inner(dap, &dpidr, &dlpidr, true);
if (retval == ERROR_OK)
break;
--
