[igt-dev] [PATCH i-g-t] tools: Add a simple tool to read/write/decode dpcd registers

[Ville Syrjälä]

On Thu, Jun 14, 2018 at 03:50:30PM +0300, Jani Nikula wrote:
> On Thu, 14 Jun 2018, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> > On Thu, Jun 14, 2018 at 12:11:41AM -0700, Tarun Vyas wrote:
> >> This tool serves as a wrapper around the constructs provided by the
> >> drm_dpcd_aux_dev kernel module by working on the /dev/drm_dp_aux[n]
> >> devices created by the kernel module.
> >> It supports reading and writing dpcd registers on the connected aux
> >> channels.
> >> In the follow-up patch, support for decoding these registers will be
> >> added to facilate debugging panel related issues.
> >> 
> >> Suggested-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> >> Signed-off-by: Tarun Vyas <tarun.vyas at intel.com>
> >> ---
> >>  tools/Makefile.am      |   2 +-
> >>  tools/Makefile.sources |   4 +-
> >>  tools/dpcd_reg.c       | 219 +++++++++++++++++++++++++++++++++++++++++++++++++
> >>  3 files changed, 223 insertions(+), 2 deletions(-)
> >>  create mode 100644 tools/dpcd_reg.c
> >> 
> >> diff --git a/tools/Makefile.am b/tools/Makefile.am
> >> index 09b6dbcc3ece..b78824dadfdb 100644
> >> --- a/tools/Makefile.am
> >> +++ b/tools/Makefile.am
> >> @@ -7,7 +7,7 @@ bin_PROGRAMS += $(LIBDRM_INTEL_BIN)
> >>  intel_error_decode_LDFLAGS = -lz
> >>  endif
> >>  
> >> -bin_PROGRAMS += intel_dp_compliance
> >> +bin_PROGRAMS += intel_dp_compliance dpcd_reg
> >
> > Not the best place for this I think.
> >
> > Missing meson.build so no one is actually going to build this.
> >
> >>  intel_dp_compliance_CFLAGS = $(AM_CFLAGS) $(GLIB_CFLAGS)
> >>  intel_dp_compliance_LDADD = $(top_builddir)/lib/libintel_tools.la
> >>  
> >> diff --git a/tools/Makefile.sources b/tools/Makefile.sources
> >> index abd23a0f4628..db606b28560f 100644
> >> --- a/tools/Makefile.sources
> >> +++ b/tools/Makefile.sources
> >> @@ -64,4 +64,6 @@ intel_dp_compliance_SOURCES = \
> >>          intel_dp_compliance.h \
> >>          intel_dp_compliance_hotplug.c \
> >>          $(NULL)
> >> -
> >> +dpcd_reg_SOURCES = \
> >> +	dpcd_reg.c \
> >> +	$(NULL)
> >> diff --git a/tools/dpcd_reg.c b/tools/dpcd_reg.c
> >> new file mode 100644
> >> index 000000000000..2848277aa792
> >> --- /dev/null
> >> +++ b/tools/dpcd_reg.c
> >> @@ -0,0 +1,219 @@
> >> +/*
> >> + * Copyright © 2018 Intel Corporation
> >> + *
> >> + * Permission is hereby granted, free of charge, to any person obtaining a
> >> + * copy of this software and associated documentation files (the "Software"),
> >> + * to deal in the Software without restriction, including without limitation
> >> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> >> + * and/or sell copies of the Software, and to permit persons to whom the
> >> + * Software is furnished to do so, subject to the following conditions:
> >> + *
> >> + * The above copyright notice and this permission notice (including the next
> >> + * paragraph) shall be included in all copies or substantial portions of the
> >> + * Software.
> >> + *
> >> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> >> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> >> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> >> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> >> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> >> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> >> + * SOFTWARE.
> >> + *
> >> + * 		DPCD register read/decode tool
> >> + * This tool wraps around DRM_DP_AUX_DEV module to provide DPCD register read,
> >> + * write and decode, so CONFIG_DRM_DP_AUX_DEV needs to be set.
> >> + */
> >> +
> >> +#include "igt_core.h"
> >> +#include <errno.h>
> >> +#include <fcntl.h>
> >> +
> >> +#define INVALID	0xff
> >> +#define RW_SIZE	1
> >> +
> >> +const char aux_dev[] = "/dev/drm_dp_aux";
> >> +
> >> +static void print_usage(char *tool, int help)
> >> +{
> >> +	igt_info("DPCD register rw and decode tool\n\n");
> >> +	igt_info("This tool requires CONFIG_DRM_DP_AUX_CHARDEV\n"
> >> +		 "to be set in the kernel config.\n");
> >> +	igt_info("Usage %s command [options...]\n", tool);
> >> +	igt_info("Supported commands are:\n"
> >> +		 "\tread: Read a dpcd reg at an offset\n"
> >> +		 "\twrite: Write a dpcd reg at an offset\n"
> >> +		 "\tdecode: Decode the value of a dpcd reg\n");
> >
> > You didn't implement decode so no point in mentioning it.
> >
> >> +	igt_info("Options for the above commands are\n"
> >> +		 "\t--device: Aux device id, IS_REQUIRED\n"
> >> +		 "\t--help: print the usage\n"
> >> +		 "\t--offset: DPCD register offset in hex, IS_REQUIRED\n"
> >> +		 "\t--spec: Specify DP/eDP spec version for decoding, IS_OPTIONAL\n"
> >> +		 "\t--val: Specify a value, for reg writes\n");
> >
> > I think you should model the UI based on intel_reg.
> 
> I originally had plans to plug this *into* intel_reg, with e.g. dpcd:
> prefix. There we have the framework ready for adding names to the
> registers using separate definition files, and we have all the
> frameworks ready for doing decoded dumps of the dpcd space. Just saying.

That's one option. But maybe people working on non-Intel hw would want
to use this as well?

-- 
Ville Syrjälä
Intel