Re: Cinergy T2 stopped working with kernel 2.6.30
I've added dummy 32-bit variables to dvb_frontend_swzigzag_autotune() to change the frame size. Here are the results for mythweb (can tune/cannot tune): #variables i486 i586 0 ok failure 1 failureok 2 ok ok 3 failurefailure 4 failureok 5 ok ok 6 ok ok 7 ok ok 8 ok failure 9 failureok 10 ok ok 11 ok failure 12 failureok 13 ok ok 14 ok ok 15 ok ok 16 ok ok 17 ok ok 18 ok failure 19 ok failure 20 failureok There's a pattern with some exceptions. Could be an alignment-related problem. Anyone listening? -- 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
Re: Cinergy T2 stopped working with kernel 2.6.30
I think I've found the problem:
static int cinergyt2_fe_set_frontend(struct dvb_frontend *fe,
struct dvb_frontend_parameters *fep)
{
struct cinergyt2_fe_state *state = fe-demodulator_priv;
struct dvbt_set_parameters_msg param;
char result[2];
int err;
param.cmd = CINERGYT2_EP1_SET_TUNER_PARAMETERS;
param.tps = cpu_to_le16(compute_tps(fep));
param.freq = cpu_to_le32(fep-frequency / 1000);
param.bandwidth = 8 - fep-u.ofdm.bandwidth - BANDWIDTH_8_MHZ;
err = dvb_usb_generic_rw(state-d,
(char *)param, sizeof(param),
result, sizeof(result), 0);
As dvbt_set_parameters_msg is declared with __attribute__((packed)), its
alignment is 8 bits. In fact, cinergyt2_fe_set_frontend()'s param variable
is not aligned on a 32-bit boundary. Note that param is passed to
usb_bulk_msg().
This seems to cause DMA problems on my hardware (Atom N270 + 945GSE + ICH7M).
I hope that I'm not talking to a black hole.
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Re: Cinergy T2 stopped working with kernel 2.6.30
On Fri, Jul 31, 2009 at 9:47 PM, emag...@magic.ms wrote: Apparently, usb_bulk_msg() cannot be used with data on the stack: http://www.linuxtv.org/pipermail/linux-dvb/2008-August/028150.html http://www.mail-archive.com/linux-usb-de...@lists.sourceforge.net/msg19158.html -- As far as I recall this has been documented for ages already... Although many people stumble over it... last but not least there's no reason to have USB drivers in the kernel anyway.. Markus -- 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
Re: Cinergy T2 stopped working with kernel 2.6.30
On Fri, Jul 31, 2009 at 08:44:59PM +0200, emag...@magic.ms wrote:
static int cinergyt2_fe_set_frontend(struct dvb_frontend *fe,
struct dvb_frontend_parameters *fep)
{
struct cinergyt2_fe_state *state = fe-demodulator_priv;
struct dvbt_set_parameters_msg param;
char result[2];
int err;
param.cmd = CINERGYT2_EP1_SET_TUNER_PARAMETERS;
param.tps = cpu_to_le16(compute_tps(fep));
param.freq = cpu_to_le32(fep-frequency / 1000);
param.bandwidth = 8 - fep-u.ofdm.bandwidth - BANDWIDTH_8_MHZ;
err = dvb_usb_generic_rw(state-d,
(char *)param, sizeof(param),
result, sizeof(result), 0);
As dvbt_set_parameters_msg is declared with __attribute__((packed)), its
alignment is 8 bits. In fact, cinergyt2_fe_set_frontend()'s param variable
is not aligned on a 32-bit boundary. Note that param is passed to
usb_bulk_msg().
This seems to cause DMA problems on my hardware (Atom N270 + 945GSE + ICH7M).
I doubt that. AFAIK EHCI has no alignment requirements on data, and the
x86 architecture has DMA consistent caches. The code in question is
broken on ARM. MIPS etc. but it should work (and according to you has
worked up to 2.6.29) on x86. (I'm not at all against fixing the
code for MIPS/ARM but I don't think that would fix the problem for you.)
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Re: Cinergy T2 stopped working with kernel 2.6.30
The more I look into this problem the stranger it becomes. I've compiled the kernel for different CPUs: |mplayer mythtv -+ CONFIG_M486 |works works CONFIG_M586 |works cannot tune CONFIG_MCORE2|cannot tune cannot tune These results are for my Atom N270 board. On my Core2 board, the Cinergy T2 works all the time. By applying -march=i486 and -march=i586 to individual source files, I found out that dvb_frontend.c is the culprit. By editing the assembly output for dvb_frontend.c, I found out that only dvb_frontend_swzigzag_autotune() needs to be compiled with CONFIG_M486 to make the Cinergy T2 work, everything else can be compiled with CONFIG_M586. Both compiled versions of dvb_frontend_swzigzag_autotune() look OK (but I haven't yet strictly verified the assembly code). Anyway, nothing in that code should make a difference on N270 vs. Core, except for timing. Adding NOPs doesn't seem to make a difference. Any ideas? Could this be a CPU bug? -- 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
Re: Cinergy T2 stopped working with kernel 2.6.30
I've now compared the generated assembly code for dvb_frontend_swzigzag_autotune() built with CONFIG_M486 vs. CONFIG_M586. Both versions are correct, but the one compiled with -march=i586 (for which tuning does not work) uses more stack space (one 32-bit word). Does this ring any bells? -- 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
Re: Cinergy T2 stopped working with kernel 2.6.30
There are two new discoveries about my Cinergy T2 problem: - the Cinergy T2 works when attached to an Intel Core2 board, but doesn't work when attached to an Intel Atom N270 board (tuning times out) - git bisect of the Linux kernel points to a bad merge of commit 60db56422043aaa455ac7f858ce23c273220f9d9 (good) and commit be0ea69674ed95e1e98cb3687a241badc756d228 (good) yielding commit 6e15cf04860074ad032e88c306bea656bbdd0f22 (bad). So, the problem is probably interrupt-related, not dvb-usb-related. Any idea on how to continue from here? -- 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
