jtag/drivers cmsis-dap: do not limit speed so strictly

Adapter clock frequency is set by 32-bit number and most adapters
limit the highest speed safely. There is no reason to impose strict
limit of 5000 kHz if some adapters can do more.

While on it give informative error message in case of zero adapter_khz.

Change-Id: I45c9804678e24496ea769ea9ca6036701b04dde9
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/3945
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

diff --git a/src/jtag/drivers/cmsis_dap_usb.c b/src/jtag/drivers/cmsis_dap_usb.c
index cffd5e7f1a60cd1df66bef47e06161e1062ba181..86f796877ba2e6dbae919d964863bd73c10fa39b 100644 (file)
--- a/src/jtag/drivers/cmsis_dap_usb.c
+++ b/src/jtag/drivers/cmsis_dap_usb.c
@@ -1499,13 +1499,11 @@ static int cmsis_dap_execute_queue(void)
 
 static int cmsis_dap_speed(int speed)
 {
-       if (speed > DAP_MAX_CLOCK) {
-               LOG_INFO("reduce speed request: %dkHz to %dkHz maximum", speed, DAP_MAX_CLOCK);
-               speed = DAP_MAX_CLOCK;
-       }
+       if (speed > DAP_MAX_CLOCK)
+               LOG_INFO("High speed (adapter_khz %d) may be limited by adapter firmware.", speed);
 
        if (speed == 0) {
-               LOG_INFO("RTCK not supported");
+               LOG_ERROR("RTCK not supported. Set nonzero adapter_khz.");
                return ERROR_JTAG_NOT_IMPLEMENTED;
        }