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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 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 Message-ID-Hash: WKXTQ3PZLOHABW2TCY2IQIA5D6JGU2QT X-Message-ID-Hash: WKXTQ3PZLOHABW2TCY2IQIA5D6JGU2QT X-MailFrom: krzysztof.kozlowski@linaro.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: alsa-devel@alsa-project.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: 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