spi-host: Fix outstanding issues (pulp-platform/snitch#394)

* spi_host: More fixes (pulp-platform/snitch#390, pulp-platform/snitch#393)

* vendor: Add `spi_host` fix

hw/vendor/lowrisc_opentitan/spi_host/rtl/spi_host_fsm.sv

@@ -291,7 +291,7 @@ module spi_host_fsm
           if (idle_cntr_q == 4'h0) begin
             prestall_st_d = WaitLead;
           end else begin
-            prestall_st_d = WaitIdle;
+            prestall_st_d = CSBSwitch;
           end
         end
         IdleCSBActive: begin
@@ -483,7 +483,7 @@ module spi_host_fsm
 
   assign wr_en_internal    = byte_starting & cmd_wr_en;
   assign shift_en_internal = bit_shifting;
-  assign rd_en_internal    = byte_ending & cmd_rd_en;
+  assign rd_en_internal    = byte_ending & cmd_rd_en_q;
   assign speed_o           = cmd_speed;
   assign sample_en_d       = byte_starting | shift_en_o;
   assign full_cyc_o        = full_cyc;

hw/vendor/patches/lowrisc_opentitan/spi_host/0004-spi_host-More-fixes-390-393.patch

@@ -0,0 +1,34 @@
+From 097522a7c17011156b55a3aab4139a82d2eb0760 Mon Sep 17 00:00:00 2001
+From: Paul Scheffler <[email protected]>
+Date: Mon, 25 Apr 2022 17:42:16 +0200
+Subject: [PATCH] spi_host: More fixes (#390, #393)
+
+---
+ rtl/spi_host_fsm.sv | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/rtl/spi_host_fsm.sv b/rtl/spi_host_fsm.sv
+index 9c28a41..3e01bff 100644
+--- a/rtl/spi_host_fsm.sv
++++ b/rtl/spi_host_fsm.sv
+@@ -291,7 +291,7 @@ module spi_host_fsm
+           if (idle_cntr_q == 4'h0) begin
+             prestall_st_d = WaitLead;
+           end else begin
+-            prestall_st_d = WaitIdle;
++            prestall_st_d = CSBSwitch;
+           end
+         end
+         IdleCSBActive: begin
+@@ -483,7 +483,7 @@ module spi_host_fsm
+
+   assign wr_en_internal    = byte_starting & cmd_wr_en;
+   assign shift_en_internal = bit_shifting;
+-  assign rd_en_internal    = byte_ending & cmd_rd_en;
++  assign rd_en_internal    = byte_ending & cmd_rd_en_q;
+   assign speed_o           = cmd_speed;
+   assign sample_en_d       = byte_starting | shift_en_o;
+   assign full_cyc_o        = full_cyc;
+-- 
+2.16.5
+