On Thu, 2011-01-20 at 16:49 -0500, Jarod Wilson wrote: > On Jan 20, 2011, at 8:22 AM, Andy Walls wrote: > > > On Wed, 2011-01-19 at 23:45 -0500, Jarod Wilson wrote: > >> On Jan 19, 2011, at 3:08 PM, Jarod Wilson wrote: > > > >>> I'm working on > >>> fixing up hdpvr-i2c further right now, and will do some more prodding > >>> with pvrusb2, the code for which looks correct with two i2c_new_device() > >>> calls in it, one for each address, so I just need to figure out why > >>> lirc_zilog is getting an -EIO trying to get tx brought up. > >> > >> So as we were discussing on irc today, the -EIO is within lirc_zilog's > >> send_boot_data() function. The firmware is loaded, and then we send the > >> z8 a command to activate the firmware, immediately follow by an attempt > >> to read the firmware version. The z8 is still busy when we do that, and > >> throwing in a simple mdelay() remedies the problem for both the hvr-1950 > >> and the hdpvr -- tried 100 initially, and all the way down to 20 still > >> worked, didn't try any lower. > > > > The Z8 on my HVR-1600 is using a 18.432 MHz crystal for its clock. > > > > The Z8 CPU Fetch and Execution units are running with a pipeline depth > > of 1: 1 insn being executed while another 1 insn is being fetched. Most > > Z8 fetch or execution cycle counts are in the range of 2-4 cycles. So > > let's just assume an insn takes 4 cycles to execute. > > > > 18.432 MHz * 20 ms = 368,640 cycles > > 368,640 cycles / 4 cycles/insn = 92,160 insns > > > > 20 ms is ~90k instructions, and seems like too long a delay to be just > > for Z8 latency. > > Some further testing today with a try-check success-delay-retry loop > shows one i2c_master_send() failure plus a udelay(100), and the second > i2c_master_send() typically always works (I haven't seen it *not* work > on the HVR-1950 in cursory testing).
Cool. > A second similar loop has proven necessary for IR TX attempts to actually > claim to succeed -- not 100% certain they really worked, as I don't have > the IR emitter with me at the moment, its at home hooked up to my hdpvr, > but I suspect its working fine now. I'm not sure I follow here. By "claim" I assume you mean no i2c_master_send() error. > > I find it interesting that for the HVR-1600 the delay isn't needed at > > all. > > > > I'm wondering if there might also be some Linux/USB latency in getting > > commands shoved over to the HVR-1950's controller (or maybe latency in > > the HVR-1950's controller too), for which this delay is really > > accounting. I suppose in kernel tracing can be used to find the latency > > on shoving things across the USB and watching for any Ack from the > > HVR-1950 controller. An experiment for some other day, I guess. > > Yeah, definitely seems to be specific to usb devices. On the plus side, > the delay loops should only add insignificant delay overhead for pci > devices, since if they work on the first call, there won't be any delay > added. Cool, nice implementation. > Oh, I've also got IR RX with ir-kbd-i2c attached to the HVR-1950 working > much better now, with the polling interval reverted to the standard > 100ms, but simply introducing the same i2c_master_send() poll that > lirc_zilog uses into get_key_haup_xvr(). You might want to check what video cards in the source tree request of, or are defaulted by, ir-kbd-i2c to use get_key_haup_xvr(). If it's only the chips at address 0x71, you're probably OK. > I want to test today's changes with the hdpvr tonight (and verify that > tx is working on the HVR-1950) before I send along my current stack of > patches, and I have suspicions that most of the hdpvr-specific crud in > lirc_zilog is bogus now -- it *should* behave exactly like the HVR-1950, > which obviously doesn't follow any of those hdpvr-specific code paths, > so I'm hoping we can rip out some additional complexity from lirc_zilog. Good riddance to old kludges. :) You could then rename the i2c client strings back to "ir_[tr]x_z8f0811_haup". We're going to modify struct IR_i2c_init_data with all the bridge specific parameters that need to be sent anyway, so no need to encode that information implicitly in the client's name anymore. Regards, Andy -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
