Re: [PATCH] ASoC: DaVinci: Added support for cpu clocking I2S
On Wed, Jun 30, 2010 at 10:17:40AM +0200, Raffaele Recalcati wrote:
2010/6/28 Mark Brown broo...@opensource.wolfsonmicro.com
It's still very hard to understand what this patch is supposed to do.
As previously mentioned this would probably be a lot clearer if you
split this into multiple patches, for example one adding support for the
fast clock mode, one adding support for selecting the pin used for any
external clock and then further patches with any other changes.
Looking at other paches, they are simpler than mine.
The big problem is you're just making some general (and not particularly
clear) statements about features without saying anything concrete about
what the patch actually does - is there a bug being fixed, a feature
implemented, or what?
Added audio playback support with [frame sync master - clock master]
mode
and with [frame sync master - clock slave].
What are these modes - which clock are you talking about?
McBSP i2s interface to external codec.
Perhaps you mean the bit clock on the I2S interface? There are multiple
clocks on the actual I2S link itself, and often people lump in the
master clock for the I2S interface into the interface itself.
i2s_fast_clock switch can be used to have better approximate or
symmetric waveforms.
Why would someone choose not to use this?
I was not sure if symmetric waveform can be a must.
In general I think it is better a non symmetric, but better approximate,
waveform.
Anyway, it is better to have the possibility to choose in my opinion,
because I have not so much experience in i2s communication.
If I understand this correctly when you say approximate what you mean
is approximate clock rate so the tradeoff is between the accuracy of
the rate generated and the duty cycle of the output signal?
+ /* To be used when cpu gets clock from extenal pin */
+ int clk_input_pin;
How would one use this?
looking at 2.5 Clock, Frames, and Data in
you can select MCBSP_CLKS or other input clock pins.
You need to put this in the comments.
+static int davinci_i2s_dai_set_clkdiv(struct snd_soc_dai *cpu_dai,
+ int div_id, int div)
+{
+ struct davinci_mcbsp_dev *dev = cpu_dai-private_data;
+ int srgr;
+
+ dev-clk_div = div;
+ return 0;
+}
I would add a clock ID here in case someone wants to configure another
clock in the patch.
Can you explain better,
please?
You need to require a value for div_id.
I'd also expect this to be doing a clk_get() using the struct device for
the DAI so that the driver can function even if the clock tree for a new..
SoC is different.
Sorry, I don't understand, can you explain me better?
clk_get() takes two parameters, a struct device and a name. You should
be using a clock specified in terms of a particular device, not one with
a NULL pointer for the struct device.
+ freq = 12200; /* FIXME ask to Texas */
...this presumably ought to be in an else clause (or perhaps just not
using this clocking at all if you can't find the clock?).
freq is used to obtain clk_div.
The real problem is that, as explained in the manual, it is not clear its
value.
I hope someone can help!!
I would very strongly expect that the division would be from the clock
rate of the source clock which you can obtain by using clk_get().
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Re: [PATCH] ASoC: DaVinci: Added support for cpu clocking I2S
The freq problem is describe here below, but it is not clear to me: From *TMS320DM36x DMSoC Multichannel Buffered Serial Port User's Guide (Rev. A) http://www.ti.com/litv/pdf/sprufi3a* 2.5.3 Data Clock Generation When the receive/transmit clock mode is set to 1 (CLK(R/X)M = 1 in the pin control register (PCR)), the data clocks (CLK(R/X)) are driven by the internal sample rate generator output clock, CLKG. You can select for the receiver and transmitter from a variety of data bit clocks including: • The input clock to the sample rate generator, which can be either the internal clock source or a dedicated external clock source via the MCBSP_CLKX, MCBSP_CLKR, or MCBSP_CLKS pins. The McBSP internal clock is the CPU/6 clock. See Section 2.5.3.1 for details on the source of the McBSP internal clock. • The input clock source (internal clock source or external clock MCBSP_CLKX/MCBSP_CLKR/MCBSP_CLKS) to the sample rate generator can be divided-down by a programmable value (CLKGDV bit in the sample rate generator register (SRGR)) to drive CLKG. Regardless of the source to the sample rate generator, the rising edge of CLKSRG (see Figure 5) generates CLKG and FSG. CPU/6 is not clear. Reading better the documentation the point seems now clear. We have pllc1 sysclk4 that is the clock of McBSP peripheral. And so it was abviously this frequency to be used when McBSP has to generate the clock. Sorry.. Raffaele ___ Davinci-linux-open-source mailing list Davinci-linux-open-source@linux.davincidsp.com http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
Re: [PATCH] ASoC: DaVinci: Added support for cpu clocking I2S
2010/6/28 Mark Brown broo...@opensource.wolfsonmicro.com
On Mon, Jun 28, 2010 at 08:44:46AM +0200, Raffaele Recalcati wrote:
From: Raffaele Recalcati raffaele.recalc...@bticino.it
It's still very hard to understand what this patch is supposed to do.
As previously mentioned this would probably be a lot clearer if you
split this into multiple patches, for example one adding support for the
fast clock mode, one adding support for selecting the pin used for any
external clock and then further patches with any other changes.
Looking at other paches, they are simpler than mine.
I'll try to split it, hoping to obtain the final result.
I strongly suggest looking at the commit messages for other patches in
the kernel and trying to follow a similar style.
Added audio playback support with [frame sync master - clock master]
mode
and with [frame sync master - clock slave].
What are these modes - which clock are you talking about?
McBSP i2s interface to external codec.
i2s_fast_clock switch can be used to have better approximate or
symmetric waveforms.
Why would someone choose not to use this?
I was not sure if symmetric waveform can be a must.
In general I think it is better a non symmetric, but better approximate,
waveform.
Anyway, it is better to have the possibility to choose in my opinion,
because I have not so much experience in i2s communication.
clk_input_pin board info can be used to select it depending on hw
connections
3. We haven't changed the evmdm365 support (due also to CPLD that
doesn't
help to understand)
We don't know in this mode if audio stereo works on evmdm365.
Probably it does.
This is what makes me unsure if you're trying to add new modes or not -
if you're adding new modes then I'd expect that existing boards would be
unaffected with any changes to use the new feature being easily
seperable.
Some tests are needed, but it requires time.
I'll try try to make some tests on evmdm365, but I'm not sure to have time
to do it.
+ /*
+ * This define works when both clock and FS are output for the cpu
+ * and makes clock very fast (FS is not simmetrical, but sampling
symmetrical.
thx
+ * frequency is better approximated
+ */
+ int i2s_fast_clock;
Is this a bool?
yes, I'll change it.
+ /* To be used when cpu gets clock from extenal pin */
+ int clk_input_pin;
+
How would one use this?
looking at 2.5 Clock, Frames, and Data in
you can select MCBSP_CLKS or other input clock pins.
From board file you can select the possibilites:
static struct snd_platform_data dm365_bmx_snd_data[] = {
{
},
{
.i2s_fast_clock = 0,
.clk_input_pin = MCBSP_CLKS,
},
};
If not set, it works as evm works, that is the default mode.
case SND_SOC_DAIFMT_CBM_CFS:
- /* McBSP CLKR pin is the input for the Sample Rate
Generator.
- * McBSP FSR and FSX are driven by the Sample Rate
Generator. */
- pcr = DAVINCI_MCBSP_PCR_SCLKME |
- DAVINCI_MCBSP_PCR_FSXM |
- DAVINCI_MCBSP_PCR_FSRM;
+ pcr = DAVINCI_MCBSP_PCR_FSRM | DAVINCI_MCBSP_PCR_FSXM;
+ if (dev-clk_input_pin == MCBSP_CLKS)
+ pcr |= DAVINCI_MCBSP_PCR_CLKXM |
+ DAVINCI_MCBSP_PCR_CLKRM;
+ else
+ /*
+ * McBSP CLKR pin is the input for the Sample Rate
+ * Generator.
+ * McBSP FSR and FSX are driven by the Sample Rate
+ * Generator.
+ */
+ pcr |= DAVINCI_MCBSP_PCR_SCLKME;
This looks like you need a switch statement for the clock selection.
ok.
+static int davinci_i2s_dai_set_clkdiv(struct snd_soc_dai *cpu_dai,
+ int div_id, int div)
+{
+ struct davinci_mcbsp_dev *dev = cpu_dai-private_data;
+ int srgr;
+
+ dev-clk_div = div;
+ return 0;
+}
+
I would add a clock ID here in case someone wants to configure another
clock in the patch.
Can you explain better,
please?
+ if (master == SND_SOC_DAIFMT_CBS_CFS) {
Use a switch staetment for this too.
+ clk = clk_get(NULL, pll1_sysclk6);
You're doing a clk_get() every time you go through here but never
freeing it - it would seem better to just do the clk_get() at startup.
Thx for this.
I think it could create problems, right?
I can do it in the probe, I think, similarly to other drivers.
I'd also expect this to be doing a clk_get() using the struct device for
the DAI so that the driver can function even if the clock tree for a new..
SoC is different.
Sorry, I don't understand, can you explain me
Re: [PATCH] ASoC: DaVinci: Added support for cpu clocking I2S
2010/6/28 Troy Kisky troy.ki...@boundarydevices.com
Raffaele Recalcati wrote:
+ if (dev-i2s_fast_clock) {
+ clk_div = 256;
can you have
f = (freq / params-rate_num) * params-rate_den;
+ do {
+ framesize = (freq / (--clk_div)) /
+ params-rate_num *
+ params-rate_den;
and
framesize = f / (--clk_div);
+ } while (((framesize 33) || (framesize 4095))
+ (clk_div));
+ clk_div--;
looks like clk_div can go negative here, should the above while say
(clk_div 1)
+ } while (((framesize 33) || (framesize 4095))
+ (clk_div));
only if clk_div not null stay inside the while.
+ clk_div--;
and here can at minumum be 0, not negative.
+ srgr |= DAVINCI_MCBSP_SRGR_FPER(framesize - 1);
+ } else {
+ /* symmetric waveforms */
+ clk_div = freq / (mcbsp_word_length * 16) /
+ params-rate_num * params-rate_den;
+ srgr |= DAVINCI_MCBSP_SRGR_FPER(mcbsp_word_length *
+ 16 - 1);
+ }
+ clk_div = 0xFF;
+ srgr |= clk_div;
so, dividing for (CLKGDV + 1) it is ok.
Raffaele
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Re: [PATCH] ASoC: DaVinci: Added support for cpu clocking I2S
On Mon, Jun 28, 2010 at 08:44:46AM +0200, Raffaele Recalcati wrote:
From: Raffaele Recalcati raffaele.recalc...@bticino.it
It's still very hard to understand what this patch is supposed to do.
As previously mentioned this would probably be a lot clearer if you
split this into multiple patches, for example one adding support for the
fast clock mode, one adding support for selecting the pin used for any
external clock and then further patches with any other changes.
I strongly suggest looking at the commit messages for other patches in
the kernel and trying to follow a similar style.
Added audio playback support with [frame sync master - clock master] mode
and with [frame sync master - clock slave].
What are these modes - which clock are you talking about?
i2s_fast_clock switch can be used to have better approximate or
symmetric waveforms.
Why would someone choose not to use this?
clk_input_pin board info can be used to select it depending on hw
connections
3. We haven't changed the evmdm365 support (due also to CPLD that doesn't
help to understand)
We don't know in this mode if audio stereo works on evmdm365.
Probably it does.
This is what makes me unsure if you're trying to add new modes or not -
if you're adding new modes then I'd expect that existing boards would be
unaffected with any changes to use the new feature being easily
seperable.
+ /*
+ * This define works when both clock and FS are output for the cpu
+ * and makes clock very fast (FS is not simmetrical, but sampling
symmetrical.
+ * frequency is better approximated
+ */
+ int i2s_fast_clock;
Is this a bool?
+ /* To be used when cpu gets clock from extenal pin */
+ int clk_input_pin;
+
How would one use this?
case SND_SOC_DAIFMT_CBM_CFS:
- /* McBSP CLKR pin is the input for the Sample Rate Generator.
- * McBSP FSR and FSX are driven by the Sample Rate Generator. */
- pcr = DAVINCI_MCBSP_PCR_SCLKME |
- DAVINCI_MCBSP_PCR_FSXM |
- DAVINCI_MCBSP_PCR_FSRM;
+ pcr = DAVINCI_MCBSP_PCR_FSRM | DAVINCI_MCBSP_PCR_FSXM;
+ if (dev-clk_input_pin == MCBSP_CLKS)
+ pcr |= DAVINCI_MCBSP_PCR_CLKXM |
+ DAVINCI_MCBSP_PCR_CLKRM;
+ else
+ /*
+ * McBSP CLKR pin is the input for the Sample Rate
+ * Generator.
+ * McBSP FSR and FSX are driven by the Sample Rate
+ * Generator.
+ */
+ pcr |= DAVINCI_MCBSP_PCR_SCLKME;
This looks like you need a switch statement for the clock selection.
+static int davinci_i2s_dai_set_clkdiv(struct snd_soc_dai *cpu_dai,
+ int div_id, int div)
+{
+ struct davinci_mcbsp_dev *dev = cpu_dai-private_data;
+ int srgr;
+
+ dev-clk_div = div;
+ return 0;
+}
+
I would add a clock ID here in case someone wants to configure another
clock in the patch.
+ if (master == SND_SOC_DAIFMT_CBS_CFS) {
Use a switch staetment for this too.
+ clk = clk_get(NULL, pll1_sysclk6);
You're doing a clk_get() every time you go through here but never
freeing it - it would seem better to just do the clk_get() at startup.
I'd also expect this to be doing a clk_get() using the struct device for
the DAI so that the driver can function even if the clock tree for a new
SoC is different.
+ if (clk)
+ freq = clk_get_rate(clk);
clk_get() returns an error pointer on error, not NULL, and...
+ freq = 12200; /* FIXME ask to Texas */
...this presumably ought to be in an else clause (or perhaps just not
using this clocking at all if you can't find the clock?).
+ } else if (master == SND_SOC_DAIFMT_CBM_CFS) {
+ /* Clock given on CLKS */
What if the user selected a different clock source?
+ if (master == SND_SOC_DAIFMT_CBS_CFS ||
+ master == SND_SOC_DAIFMT_CBS_CFM) {
Again, switch statement.
+ if (master == SND_SOC_DAIFMT_CBS_CFS ||
+ master == SND_SOC_DAIFMT_CBS_CFM) {
Here too.
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