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bh=9DcxmSY88sa/IFq/9pI8Ul8RolH6HxvF4wzvh7XRi4E=; b=L6/aH8sHQSj5FIg54ozx8gVU9zRM96vD9SGvib+ARivRLj08b/LQ1tT3/cZpwo2ZyyYnH2 Q0h6z9nfeykNKE8PEEHGF4PxF9dKAu9Zl9qqrAbvQrPxrbcIZbkgZdbEczELtygrgeFa0y Go9tTYe2KYHb1hoXy1A3RwFP9xipG9wyc2tRi0pcFmNVtrCXvdC4gOtR512mMVIJy7/77u O820dOAfz76YI2bmZwQkpVgcQf2/W1odBzZZFEuoX31iBVvR7fHz83ItwD/Bd8yblxj6+H Bwn8Q92kDgyqgyOH9eI5jzRhOwP6WcgAmfz5iA1noZ/1w9/y3W7zKAY+9chfag== From: Miquel Raynal To: Santhosh Kumar K Cc: , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH v2 01/12] spi: dt-bindings: add spi-has-dqs property In-Reply-To: <20260113141617.1905039-2-s-k6@ti.com> (Santhosh Kumar K.'s message of "Tue, 13 Jan 2026 19:46:06 +0530") References: <20260113141617.1905039-1-s-k6@ti.com> <20260113141617.1905039-2-s-k6@ti.com> User-Agent: mu4e 1.12.7; emacs 30.2 Date: Wed, 04 Feb 2026 11:46:45 +0100 Message-ID: <87wm0sg50q.fsf@bootlin.com> MIME-Version: 1.0 X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260204_024653_422322_6C39A760 X-CRM114-Status: GOOD ( 17.22 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; 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bh=9DcxmSY88sa/IFq/9pI8Ul8RolH6HxvF4wzvh7XRi4E=; b=L6/aH8sHQSj5FIg54ozx8gVU9zRM96vD9SGvib+ARivRLj08b/LQ1tT3/cZpwo2ZyyYnH2 Q0h6z9nfeykNKE8PEEHGF4PxF9dKAu9Zl9qqrAbvQrPxrbcIZbkgZdbEczELtygrgeFa0y Go9tTYe2KYHb1hoXy1A3RwFP9xipG9wyc2tRi0pcFmNVtrCXvdC4gOtR512mMVIJy7/77u O820dOAfz76YI2bmZwQkpVgcQf2/W1odBzZZFEuoX31iBVvR7fHz83ItwD/Bd8yblxj6+H Bwn8Q92kDgyqgyOH9eI5jzRhOwP6WcgAmfz5iA1noZ/1w9/y3W7zKAY+9chfag== From: Miquel Raynal To: Santhosh Kumar K Cc: , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH v2 01/12] spi: dt-bindings: add spi-has-dqs property In-Reply-To: <20260113141617.1905039-2-s-k6@ti.com> (Santhosh Kumar K.'s message of "Tue, 13 Jan 2026 19:46:06 +0530") References: <20260113141617.1905039-1-s-k6@ti.com> <20260113141617.1905039-2-s-k6@ti.com> User-Agent: mu4e 1.12.7; emacs 30.2 Date: Wed, 04 Feb 2026 11:46:45 +0100 Message-ID: <87wm0sg50q.fsf@bootlin.com> Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 On 13/01/2026 at 19:46:06 +0530, Santhosh Kumar K wrote: > Add the optional 'spi-has-dqs' boolean property for SPI flash device > subnodes. This property indicates the flash device supports DQS (Data > Strobe) mode, which provides improved timing margins for data capture > in high-speed SPI operations. > > Signed-off-by: Santhosh Kumar K > --- > .../devicetree/bindings/spi/spi-peripheral-props.yaml | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.y= aml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > index 8b6e8fc009db..c6f330fd32aa 100644 > --- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > +++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > @@ -89,6 +89,12 @@ properties: > description: > Delay, in microseconds, after a write transfer. >=20=20 > + spi-has-dqs: > + description: > + Indicates the SPI flash device supports DQS (Data Strobe) mode for > + improved data capture timing. > + $ref: /schemas/types.yaml#/definitions/flag This information is currently lacking indeed, mostly because nobody ever cared about it. The DT property is IMO not the correct way to give this information for two reasons: - this is a capability of the chip, we discover the chip dynamically in both cases (NAND and NOR) and attach many capabilities to the chips already, so I believe this information should be provided through a flag. - the fact that the DQS signal might be supported does not indicate it is actually driven. Winbond chips, for instance, can either enable it or not depending on their configuration (probably through their VCR register, I need to check again). The question I have is: shall we enable the DQS pin automatically if it is available? Not all controllers support it I suppose, and wiring the line might as well not be done (or incorrectly). For these cases we may need DT properties in the future. But for the DQS presence indication, I bet it is not useful, and should be handled at the core level (not parsed by the driver like you do) because it may have an impact on the chip internal configuration. I will try to come up with a proposal soon! Cheers, Miqu=C3=A8l