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X-CSE-ConnectionGUID: BApjExqiTim3RzQByOk0ww== X-CSE-MsgGUID: iDKTPwRRQ865FqjgcAKOpA== X-IronPort-AV: E=McAfee;i="6700,10204,11206"; a="26482948" X-IronPort-AV: E=Sophos;i="6.10,257,1719903600"; d="scan'208";a="26482948" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2024 08:05:25 -0700 X-CSE-ConnectionGUID: uBmKSm89TSiRGkjsbpUpYg== X-CSE-MsgGUID: ELGXt5SjQ5GvFpL3sot2/g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,257,1719903600"; d="scan'208";a="76317739" Received: from kniemiec-mobl1.ger.corp.intel.com (HELO [10.245.246.30]) ([10.245.246.30]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2024 08:05:20 -0700 Message-ID: <8bb65adc-e995-443e-80c9-36e9b5d8eee3@linux.intel.com> Date: Wed, 25 Sep 2024 16:54:28 +0200 Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v28 30/32] ALSA: usb-audio: Add USB offload route kcontrol To: Wesley Cheng , srinivas.kandagatla@linaro.org, mathias.nyman@intel.com, perex@perex.cz, conor+dt@kernel.org, dmitry.torokhov@gmail.com, corbet@lwn.net, broonie@kernel.org, lgirdwood@gmail.com, tiwai@suse.com, krzk+dt@kernel.org, Thinh.Nguyen@synopsys.com, bgoswami@quicinc.com, robh@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-sound@vger.kernel.org, linux-input@vger.kernel.org, linux-usb@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-doc@vger.kernel.org, alsa-devel@alsa-project.org References: <20240925010000.2231406-1-quic_wcheng@quicinc.com> <20240925010000.2231406-31-quic_wcheng@quicinc.com> Content-Language: en-US From: Pierre-Louis Bossart In-Reply-To: <20240925010000.2231406-31-quic_wcheng@quicinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit > +static int > +snd_usb_offload_route_get(struct snd_kcontrol *kcontrol, > + struct snd_ctl_elem_value *ucontrol) > +{ > + struct device *sysdev = snd_kcontrol_chip(kcontrol); > + int ret; > + > + ret = snd_soc_usb_update_offload_route(sysdev, > + CARD_IDX(kcontrol->private_value), > + PCM_IDX(kcontrol->private_value), > + SNDRV_PCM_STREAM_PLAYBACK, > + ucontrol->value.integer.value); > + if (ret < 0) { > + ucontrol->value.integer.value[0] = -1; > + ucontrol->value.integer.value[1] = -1; > + } well this invalidates again what I understood from the last patch and goes back to what I understood initially: the error code is never returned to higher levels - when offload is not supported the kcontrol values are encoded to the -1 magic value. > + return 0; and this begs the question if this helper should return a void value. > +} > + > +static int snd_usb_offload_route_info(struct snd_kcontrol *kcontrol, > + struct snd_ctl_elem_info *uinfo) > +{ > + uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER; > + uinfo->count = 2; > + uinfo->value.integer.min = -1; > + /* Arbitrary max value, as there is no 'limit' on number of PCM devices */ > + uinfo->value.integer.max = 0xff; > + > + return 0; > +} > + > +static struct snd_kcontrol_new snd_usb_offload_mapped_ctl = { > + .iface = SNDRV_CTL_ELEM_IFACE_CARD, > + .access = SNDRV_CTL_ELEM_ACCESS_READ, > + .info = snd_usb_offload_route_info, > + .get = snd_usb_offload_route_get, > +}; > + > +/** > + * snd_usb_offload_create_ctl() - Add USB offload bounded mixer > + * @chip - USB SND chip device > + * > + * Creates a sound control for a USB audio device, so that applications can > + * query for if there is an available USB audio offload path, and which > + * card is managing it. > + */ > +int snd_usb_offload_create_ctl(struct snd_usb_audio *chip) > +{ > + struct usb_device *udev = chip->dev; > + struct snd_kcontrol_new *chip_kctl; > + struct snd_usb_substream *subs; > + struct snd_usb_stream *as; > + char ctl_name[37]; that's quite a magic value. > + int ret; > + > + list_for_each_entry(as, &chip->pcm_list, list) { > + subs = &as->substream[SNDRV_PCM_STREAM_PLAYBACK]; > + if (!subs->ep_num) > + continue; > + > + chip_kctl = &snd_usb_offload_mapped_ctl; > + chip_kctl->count = 1; > + /* > + * Store the associated USB SND card number and PCM index for > + * the kctl. > + */ > + chip_kctl->private_value = as->pcm_index | > + chip->card->number << 16; > + sprintf(ctl_name, "USB Offload Playback Route PCM#%d", > + as->pcm_index); > + chip_kctl->name = ctl_name; > + ret = snd_ctl_add(chip->card, snd_ctl_new1(chip_kctl, > + udev->bus->sysdev)); > + if (ret < 0) > + break; > + } > + > + return ret; > +}