Fix error on exit with uninitialized target

[tom-van]

riscv_deinit_target() tries to get_target_type() even if the examination failed or was not called at all. dtm_version is not known and an annoying error is printed:

Error: [riscv.cpu.0] Unsupported DTM version: -1
Error: [riscv.cpu.0] Could not identify target type.

Avoid calling get_target_type() if dtm_version is
DTM_DTMCS_VERSION_UNKNOWN.

Change-Id: I48239b1b11561357e845f3a6cb3a8e3b19e35715

[en-sc]

Thank you for the patch! I also find these messages annoying, but there is an underlying issue -- a proper deinitialization can not be guaranteed in such cases for now. So, IMHO, a message should be printed here.

[en-sc]

This is not particularly safe. Please, consider a target that was not properly initialized. target->arch_info can be still zero or point to uninitialized memory.
The condition should at least be modified to:

if (info && info->dtm_version != DTM_DTMCS_VERSION_UNKNOWN) {

However, under such condition get_target_type() will never print an error, and IMHO, if a target was never initialized but riscv_deinit_target() is called -- an error should be printed.

In general, I would like to leave the messaging here.
In case examine() failed, the state of the target is not the same as if the target was just initialized. Moreover, it is not documented either. This is an issue. I am preparing some patches aimed at addressing this. BTW, your patch with riscv013_dm_free() is a great help in this regard, thanks!

If you still find the message too annoying -- please, consider changing it to LOG_TARGET_DEBUG().

[tom-van]

The condition should at least be modified to:

if (info && info->dtm_version != DTM_DTMCS_VERSION_UNKNOWN) {

Good point, will fix if we go on with this patch.

In case examine() failed, the state of the target is not the same as if the target was just initialized. Moreover, it is not documented either. This is an issue. I am preparing some patches aimed at addressing this.

Oh I think I see at least one issue:
If tt->init_target() succeds
https://github.com/riscv/riscv-openocd/blob/5d4fa0001e2f6bd23caf10fd02f980053adb2b3b/src/target/riscv/riscv.c#L1740
and the following version specific examination fails
https://github.com/riscv/riscv-openocd/blob/5d4fa0001e2f6bd23caf10fd02f980053adb2b3b/src/target/riscv/riscv.c#L1744-L1746
dtm_version gets reset to unknown
https://github.com/riscv/riscv-openocd/blob/5d4fa0001e2f6bd23caf10fd02f980053adb2b3b/src/target/riscv/riscv.c#L1750-L1752
and later
https://github.com/riscv/riscv-openocd/blob/5d4fa0001e2f6bd23caf10fd02f980053adb2b3b/src/target/riscv/riscv.c#L533
will not recognize target type and therefore will not call
https://github.com/riscv/riscv-openocd/blob/5d4fa0001e2f6bd23caf10fd02f980053adb2b3b/src/target/riscv/riscv.c#L545-L546

Hmm, much worse than an annoying message. Giving up for now