bif: qpnp-bsi: correct maximum transaction delay time
The value QPNP_BSI_MAX_TRANSMIT_CYCLES is used to define the
timeout interval when sending or receiving BIF data words.
The MIPI-BIF specification allows for some skew in the length
of bits received from a slave. A '1' can take up to 3.5 tau_bif
and a '0' can take up to 1.5 tau_bif. Therefore, the maximum word
transmission time can be calculated as follows.
max-transmission-time =
= n(1)_max * t(1)_max + (17 - n(1)_max) * t(0)_max + t(stop)_min
= 8 * 3.5 tau_bif + 9 * 1.5 tau_bif + 4.5 tau_bif
= 46 tau_bif
Change QPNP_BSI_MAX_TRANSMIT_CYCLES to 46 in order to match the
value calculated from the MIPI-BIF specification.
Change-Id: Ibb199b54c99cc2de29ae54f6f891a667a30213b2
Signed-off-by: David Collins <collinsd@codeaurora.org>
diff --git a/drivers/bif/qpnp-bsi.c b/drivers/bif/qpnp-bsi.c
index 19a560a..2fc0f4f 100644
--- a/drivers/bif/qpnp-bsi.c
+++ b/drivers/bif/qpnp-bsi.c
@@ -170,7 +170,7 @@
#define QPNP_BSI_DEFAULT_VID_REF_UV 1800000
/* These have units of tau_bif. */
-#define QPNP_BSI_MAX_TRANSMIT_CYCLES 36
+#define QPNP_BSI_MAX_TRANSMIT_CYCLES 46
#define QPNP_BSI_MIN_RECEIVE_CYCLES 24
#define QPNP_BSI_MAX_BUS_QUERY_CYCLES 17