Hello, This is a multi-part review of the series, with general notes inline in this message, and specific points raised as replies to the individual patches. On Mon, Apr 13, 2020 at 03:29:14PM -0700, Ernesto Corona wrote: > We propose to implement general JTAG interface and infrastructure > to communicate with user layer application. Working with a Tioga Pass server platform I needed to use the JTAG master controller of an ASPEED AST2500 SoC to configure a Lattice LCMXO2-4000HC CPLD. I'm mentioning these fine details because that's the only proper runtime testing I performed, but my review is not limited to that. Being a long-time OpenOCD community member, I got familiar with many different facilities and protocols offered by hardware JTAG adapters, and of wide range of usecases as I was providing end-user support. This is my perspective when looking at these patches. I have to note that the current v29 version of the series is broken in several aspects: 1. The aspeed driver fails probe(), see the driver review for details; 2. The uapi include header is unusable; 3. The offered userspace implementation wasn't updated to the latest API, but even with the changes to make it compile it's still a mess too horrible to be used in production; Points 1 and 2 will be addressed in separate mails. To workaround point 3 I prepared a recipe with an additional patch[0] so that mlnx_cpldprog can be at least compiled and used for some minimal testing. The shortcomings of mlnx_cpldprog are numerous: 1. It doesn't consistently choose between hardware and bitbang modes; 2. Even though it checks TDO it doesn't print any errors on mismatch and continues playing back the SVF as if it's all right; 3. It has JTAG speed hardcoded; 4. It doesn't implement RUNTEST so with the CPLD I'm using it's always _not_ working properly, failing silently; 5. It is just awfully slow, taking about 40 minutes to play back a file that takes 1.5 minutes with OpenOCD with the same hardware and kernel driver. So I added support for the proposed API to OpenOCD: patch that applies to the version in OpenBMC[1], patch for the latest version[2]. And since it can do much more than just playing back SVF I hope this can highlight some essential API shortcomings if it's meant to be generic. My impression is that in its current state it's not adequate for the purpose. [0] https://bitbucket.org/paulfertser/mlnx_cpldprog_bitbake [1] http://openocd.zylin.com/#/c/5976/ [2] http://openocd.zylin.com/#/c/5975/ -- Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software! mailto:fercerpav@xxxxxxxxx
