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/+/7213
-- gerrit
commit bd8ca58f1922f823c2337b5324b84f9cf2b26bdd
Author: Tomas Vanek <van...@fbl.cz>
Date: Tue Sep 20 18:55:51 2022 +0200
target/adi_v5_swd: fix SWD multidrop
Implementation of ADI v6 introduced banking of DP reg 0.
The accompanying change preventing DP SELECT write before
DP IDR read during connect was added to swd_connect_single() only.
Unchanged swd_connect_multidrop() / swd_multidrop_select_inner()
was broken as it emited DP SELECT and put DP to protocol error state.
Copy dap->select handling to swd_multidrop_select_inner().
Fixes: 72fb88613f02 (adiv6: add low level swd transport)
Change-Id: I514cd6d9ae2ba97ce3657b459df22638c278a0b1
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 979c643e90..512d0934b9 100644
--- a/src/target/adi_v5_swd.c
+++ b/src/target/adi_v5_swd.c
@@ -177,6 +177,19 @@ 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)
@@ -186,6 +199,8 @@ static int swd_multidrop_select_inner(struct adiv5_dap
*dap, uint32_t *dpidr_ptr
if (retval != ERROR_OK)
return retval;
+ dap->select = DP_SELECT_INVALID;
+
if (clear_sticky) {
/* Clear all sticky errors (including ORUN) */
swd_clear_sticky_errors(dap);
@@ -342,6 +357,7 @@ static int swd_connect_single(struct adiv5_dap *dap)
dap->switch_through_dormant = !dap->switch_through_dormant;
} while (timeval_ms() < timeout);
+
dap->select = DP_SELECT_INVALID;
if (retval != ERROR_OK) {
--
