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Thu, 16 Feb 2023 02:43:58 -0800 (PST) Received: from [192.168.1.109] ([178.197.216.144]) by smtp.gmail.com with ESMTPSA id oq15-20020a170906cc8f00b008b165948da6sm490473ejb.101.2023.02.16.02.43.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Feb 2023 02:43:47 -0800 (PST) Message-ID: Date: Thu, 16 Feb 2023 11:43:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH 2/3] ASoC: dt-bindings: sama7g5-pdmc: add microchip,startup-delay-us binding Content-Language: en-US To: Claudiu.Beznea@microchip.com, lgirdwood@gmail.com, broonie@kernel.org, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, lars@metafoo.de, perex@perex.cz, tiwai@suse.com, Nicolas.Ferre@microchip.com, alexandre.belloni@bootlin.com Cc: alsa-devel@alsa-project.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20230214161435.1088246-1-claudiu.beznea@microchip.com> <20230214161435.1088246-3-claudiu.beznea@microchip.com> <485d74fe-bfb5-c55e-724f-304476624abd@linaro.org> <954cdf90-c41a-4e21-31e0-88a0baf26065@microchip.com> <8a2132f6-9745-5ef2-724e-14e76fc456f0@microchip.com> From: Krzysztof Kozlowski In-Reply-To: <8a2132f6-9745-5ef2-724e-14e76fc456f0@microchip.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 16/02/2023 11:41, Claudiu.Beznea@microchip.com wrote: > On 16.02.2023 12:18, Krzysztof Kozlowski wrote: >> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >> >> On 16/02/2023 11:15, Claudiu.Beznea@microchip.com wrote: >>> On 16.02.2023 12:04, Krzysztof Kozlowski wrote: >>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >>>> >>>> On 14/02/2023 17:14, Claudiu Beznea wrote: >>>>> Add microchip,startup-delay-us binding to let PDMC users to specify >>>>> startup delay. >>>>> >>>>> Signed-off-by: Claudiu Beznea >>>>> --- >>>>> .../devicetree/bindings/sound/microchip,sama7g5-pdmc.yaml | 6 ++++++ >>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/sound/microchip,sama7g5-pdmc.yaml b/Documentation/devicetree/bindings/sound/microchip,sama7g5-pdmc.yaml >>>>> index c4cf1e5ab84b..9b40268537cb 100644 >>>>> --- a/Documentation/devicetree/bindings/sound/microchip,sama7g5-pdmc.yaml >>>>> +++ b/Documentation/devicetree/bindings/sound/microchip,sama7g5-pdmc.yaml >>>>> @@ -67,6 +67,12 @@ properties: >>>>> maxItems: 4 >>>>> uniqueItems: true >>>>> >>>>> + microchip,startup-delay-us: >>>>> + description: | >>>>> + Specifies the delay in microseconds that needs to be applied after >>>>> + enabling the PDMC microphones to avoid unwanted noise due to microphones >>>>> + not being ready. >>>> >>>> Is this some hardware delay? Or OS? If OS, why Linux specific delay is >>>> put into DT? >>> >>> It's the delay used in software workaround that IP needs to filter noises. >> >> Then this sounds like OS? Linux related properties usually do not belong >> to DT. >> >>> The IP is not fully featured to do this kind of filtering on its own thus >>> this software workaround. This delay may depend on used microphones thus >>> for different kind of setups (PDMC + different microphones) I introduced >>> this in DT. >> >> I understand your driver needs delay and I am not questioning this. I am >> questioning why this is suitable for DT? > > Because that delay may depend on the microphones that are used with PDMC. > Different boards may come with different microphones, thus the default > delay may not fit to fully filter the noise. Due to this I chose to add it > in DT. Ah, ok, that's good explanation. Thank you. Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof