From: Dmitry Osipenko <digetx@gmail.com> To: Jon Hunter <jonathanh@nvidia.com>, Thierry Reding <thierry.reding@gmail.com>, Mark Brown <broonie@kernel.org>, Takashi Iwai <tiwai@suse.com>, Jaroslav Kysela <perex@perex.cz>, Ion Agorria <ion@agorria.com>, Svyatoslav Ryhel <clamor95@gmail.com>, Liam Girdwood <lgirdwood@gmail.com> Cc: alsa-devel@alsa-project.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] ASoC: tegra: Unify ASoC machine drivers Date: Mon, 24 May 2021 16:40:30 +0300 [thread overview] Message-ID: <f9631faa-5fc8-ecdd-709b-93b58e45a1ac@gmail.com> (raw) In-Reply-To: <6bc26992-e136-ef6a-a956-382b5cae5db7@nvidia.com> 24.05.2021 15:22, Jon Hunter пишет: > > > On 21/05/2021 20:05, Dmitry Osipenko wrote: > > ... > >>>> +unsigned int tegra_asoc_machine_mclk_rate(unsigned int srate) >>>> +{ >>>> + unsigned int mclk; >>>> + >>>> + switch (srate) { >>>> + case 64000: >>>> + case 88200: >>>> + case 96000: >>>> + mclk = 128 * srate; >>>> + break; >>>> + default: >>>> + mclk = 256 * srate; >>>> + break; >>>> + } >>>> + /* FIXME: Codec only requires >= 3MHz if OSR==0 */ >>>> + while (mclk < 6000000) >>>> + mclk *= 2; >>> >>> So this appears to be specific to the wm8903 codec or at least this is >>> where it came from. And given that the switch statement is not complete >>> in terms of the sample rates (ie. only has a subset), I am wondering if >>> set should keep this specific to the wm8903 codec? >> >> The RT5631 codec of Asus Transformers will re-use this function. > > OK, but does it need this FIXME part? That appears to be codec specific. Downstream RT5631 Tegra driver has exactly the same FIXME. Although, I now see that downstream RT5631 uses 384*srate for the default cases. I also see that WM8994 driver that we have in grate-kernel for Galaxy Tab and SGH-I927 also re-uses that mclk_rate function. >> IIUC, the default switch-case works properly for all rates below 64KHz, >> at least I haven't had any problems with it. Could you please clarify >> why you are saying that the switch statement appears to be incomplete? > > It looks a bit weird because less than 64kHz and greater than 96kHz we > use 256 and for only 64kHz, 88.2kHz and 96kHz we use 128. So it is not > clear to me which sample rates have actually been tested with this and > if this is complete or not? > > Is it intended that we use 256 for sample rates greater than 96kHz? The 128*srate gives MCLK >6MHZ for 64/88/96, 256*srate gives MCLK >6MHZ for rates below 64kHZ. Looks like the goal is to get MCLK >6MHZ. The WM8903 datasheet says: "The following operating frequency limits must be observed when configuring CLK_SYS. Failure to observe these limits will result in degraded noise performance and/or incorrect ADC/DAC functionality. If DAC_OSR = 0 then CLK_SYS 3MHz If DAC_OSR = 1 then CLK_SYS 6MHz" Where DAC_OSR is DAC Oversampling Control 0 = Low power (normal oversample) 1 = High performance (double rate) I see that DAC_OSR=0 by default, it can be switched to 1 by userspace ALSA control.
WARNING: multiple messages have this Message-ID (diff)
From: Dmitry Osipenko <digetx@gmail.com> To: Jon Hunter <jonathanh@nvidia.com>, Thierry Reding <thierry.reding@gmail.com>, Mark Brown <broonie@kernel.org>, Takashi Iwai <tiwai@suse.com>, Jaroslav Kysela <perex@perex.cz>, Ion Agorria <ion@agorria.com>, Svyatoslav Ryhel <clamor95@gmail.com>, Liam Girdwood <lgirdwood@gmail.com> Cc: linux-tegra@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] ASoC: tegra: Unify ASoC machine drivers Date: Mon, 24 May 2021 16:40:30 +0300 [thread overview] Message-ID: <f9631faa-5fc8-ecdd-709b-93b58e45a1ac@gmail.com> (raw) In-Reply-To: <6bc26992-e136-ef6a-a956-382b5cae5db7@nvidia.com> 24.05.2021 15:22, Jon Hunter пишет: > > > On 21/05/2021 20:05, Dmitry Osipenko wrote: > > ... > >>>> +unsigned int tegra_asoc_machine_mclk_rate(unsigned int srate) >>>> +{ >>>> + unsigned int mclk; >>>> + >>>> + switch (srate) { >>>> + case 64000: >>>> + case 88200: >>>> + case 96000: >>>> + mclk = 128 * srate; >>>> + break; >>>> + default: >>>> + mclk = 256 * srate; >>>> + break; >>>> + } >>>> + /* FIXME: Codec only requires >= 3MHz if OSR==0 */ >>>> + while (mclk < 6000000) >>>> + mclk *= 2; >>> >>> So this appears to be specific to the wm8903 codec or at least this is >>> where it came from. And given that the switch statement is not complete >>> in terms of the sample rates (ie. only has a subset), I am wondering if >>> set should keep this specific to the wm8903 codec? >> >> The RT5631 codec of Asus Transformers will re-use this function. > > OK, but does it need this FIXME part? That appears to be codec specific. Downstream RT5631 Tegra driver has exactly the same FIXME. Although, I now see that downstream RT5631 uses 384*srate for the default cases. I also see that WM8994 driver that we have in grate-kernel for Galaxy Tab and SGH-I927 also re-uses that mclk_rate function. >> IIUC, the default switch-case works properly for all rates below 64KHz, >> at least I haven't had any problems with it. Could you please clarify >> why you are saying that the switch statement appears to be incomplete? > > It looks a bit weird because less than 64kHz and greater than 96kHz we > use 256 and for only 64kHz, 88.2kHz and 96kHz we use 128. So it is not > clear to me which sample rates have actually been tested with this and > if this is complete or not? > > Is it intended that we use 256 for sample rates greater than 96kHz? The 128*srate gives MCLK >6MHZ for 64/88/96, 256*srate gives MCLK >6MHZ for rates below 64kHZ. Looks like the goal is to get MCLK >6MHZ. The WM8903 datasheet says: "The following operating frequency limits must be observed when configuring CLK_SYS. Failure to observe these limits will result in degraded noise performance and/or incorrect ADC/DAC functionality. If DAC_OSR = 0 then CLK_SYS 3MHz If DAC_OSR = 1 then CLK_SYS 6MHz" Where DAC_OSR is DAC Oversampling Control 0 = Low power (normal oversample) 1 = High performance (double rate) I see that DAC_OSR=0 by default, it can be switched to 1 by userspace ALSA control.
next prev parent reply other threads:[~2021-05-24 13:40 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-20 17:50 [PATCH v2 0/2] Unify NVIDIA Tegra ASoC machine drivers Dmitry Osipenko 2021-05-20 17:50 ` Dmitry Osipenko 2021-05-20 17:50 ` [PATCH v2 1/2] ASoC: tegra: Set driver_name=tegra for all " Dmitry Osipenko 2021-05-20 17:50 ` Dmitry Osipenko 2021-05-20 18:12 ` Dmitry Osipenko 2021-05-20 18:12 ` Dmitry Osipenko 2021-05-20 17:50 ` [PATCH v2 2/2] ASoC: tegra: Unify ASoC " Dmitry Osipenko 2021-05-20 17:50 ` Dmitry Osipenko 2021-05-20 19:02 ` Jaroslav Kysela 2021-05-20 19:02 ` Jaroslav Kysela 2021-05-20 19:08 ` Mark Brown 2021-05-20 19:08 ` Mark Brown 2021-05-21 8:54 ` Jaroslav Kysela 2021-05-21 8:54 ` Jaroslav Kysela 2021-05-21 18:43 ` Dmitry Osipenko 2021-05-21 18:43 ` Dmitry Osipenko 2021-05-21 13:12 ` Jon Hunter 2021-05-21 13:12 ` Jon Hunter 2021-05-21 19:05 ` Dmitry Osipenko 2021-05-21 19:05 ` Dmitry Osipenko 2021-05-24 12:22 ` Jon Hunter 2021-05-24 12:22 ` Jon Hunter 2021-05-24 13:40 ` Dmitry Osipenko [this message] 2021-05-24 13:40 ` Dmitry Osipenko 2021-05-24 18:50 ` Jon Hunter 2021-05-24 18:50 ` Jon Hunter 2021-05-24 21:02 ` Dmitry Osipenko 2021-05-24 21:02 ` Dmitry Osipenko 2021-05-25 6:51 ` Jon Hunter 2021-05-25 6:51 ` Jon Hunter
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