Hi, On 09/12/2016 06:35 PM, rijure...@mpi-sws.org wrote: > Currently, I am browsing the android source code folders, to find "camera > device driver" related code. What is a more systematic way to understand > what happens at the systems level between "pressing a camera button" -- > "pressing the capture button" -- "saving the picture" in an android > phone/tablet? > > Can something like systrace > (http://www.vogella.com/tutorials/AndroidTools/article.html#systrace), be > used to see what kernel functions are invoked? Is such tracing supported > on android 2.3.7, on which the demo is based? Did you use any such tool to > understand the necessary code related to touchscreen/display/capacitive > sensors, which you then moved to the secure world? >
I don't know. I never used systrace before (only strace). When looking at the behaviour of the Linux kernel drivers for IPU and touchscreen, I simply traced all memory mapped I/O accesses by introducing corresponding printks manually (__raw_read* and __raw_write* in io.h). By studying the output, the documentation, and in case of doubts the Linux kernel code, I implemented the corresponding IPU functionality. Regards Stefan > Thanks! > Riju > >> I can run the SABRE tablet Genode demo: >> https://github.com/skalk/genode/blob/i.MX53_tablet_demo/os/src/server/vmm/imx53/README. >> The demo is on SD card, and the android is on e-mmc. According to >> https://sourceforge.net/p/genode/mailman/message/33919618/, I changed the >> e-mmc android to imx-android-r10.4_bundle_BSP.tar.gz, so that it matches >> the android kernel in the genode demo. >> >> I can use the front camera of the SABRE tablet to take pictures, when >> android is started directly from emmc (sw26 and sw28 reconfigured). But >> when I boot the genode demo and then start android from within it, >> pressing the camera icon says “Cannot connect to camera”. >> >> Question 1: I understand that the genode demo needed the display, >> touchscreen and capacitive sensors kernel code to be moved to secure >> world. Did that screw up the camera functionality of the android in the >> normal world? Maybe the camera needs the display for preview, which it >> cannot get? Did your secure-world implementation of the >> display/touchscreen/capacitive sensor drivers come with some APIs, that >> the normal world should call to access forbidden resources? Are those APIs >> part of the normal world kernel and uses the smc() functionality to >> request forbidden resources? Does that mean that the camera is failing, as >> it is not calling the proper API to request the display? >> >> Question 2: My goal is to move the camera device driver to the secure >> world. At http://genode.org/documentation/articles/trustzone, under the >> section “Additional Device Driver”, you say that “The task of CREATING the >> drivers…”. I understand that the android in e-mmc already supported the >> display, touchscreen and capacitive sensors. So couldn’t you look at the >> android source and see where these drivers are, instead of creating these >> drivers using the documentation? Since I need to repeat the process of >> moving the camera device drivers from the normal to the secure world, some >> more details of how you approached the problem for >> touchscreen/display/capacitive sensor will be super useful. For example, >> looking at the source code of imx-android-r10.4_bundle_BSP.tar.gz, I can >> see >> >> $ls ~/myandroid/hardware/mx5x/libcamera/ >> Android.mk Camera_pmem.cpp CaptureDeviceInterface.cpp >> JpegEncoderInterface.h PostProcessDeviceInterface.cpp PP_ipulib.h >> V4l2CsiDevice.cpp >> CameraHal.cpp Camera_pmem.h CaptureDeviceInterface.h >> JpegEncoderSoftware.cpp PostProcessDeviceInterface.h >> V4l2CapDeviceBase.cpp V4l2CsiDevice.h >> CameraHal.h Camera_utils.h JpegEncoderInterface.cpp >> JpegEncoderSoftware.h PP_ipulib.cpp >> V4l2CapDeviceBase.h V4l2UVCDevice.h >> >> Do some of those needed to be moved to the secure world kernel, or do we >> need to write a camera device driver from scratch? >> >> Thanks! >> Riju >> >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> genode-main mailing list >> genode-main@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/genode-main >> > > > ------------------------------------------------------------------------------ > What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic > patterns at an interface-level. Reveals which users, apps, and protocols are > consuming the most bandwidth. Provides multi-vendor support for NetFlow, > J-Flow, sFlow and other flows. Make informed decisions using capacity > planning reports. http://sdm.link/zohodev2dev > _______________________________________________ > genode-main mailing list > genode-main@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/genode-main > -- Stefan Kalkowski Genode Labs https://github.com/skalk · http://genode.org/ ------------------------------------------------------------------------------ _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main
