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Thu, 16 Feb 2023 02:18:20 -0800 (PST) Received: from [192.168.1.109] ([178.197.216.144]) by smtp.gmail.com with ESMTPSA id x17-20020a1709064a9100b008b12614ee06sm610840eju.161.2023.02.16.02.18.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Feb 2023 02:18:19 -0800 (PST) Message-ID: Date: Thu, 16 Feb 2023 11:18:16 +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> From: Krzysztof Kozlowski In-Reply-To: <954cdf90-c41a-4e21-31e0-88a0baf26065@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 11:15, 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? Best regards, Krzysztof