From: Rob Herring <robh@kernel.org>
To: Aswath Govindraju <a-govindraju@ti.com>
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Vadym Kochan <vadym.kochan@plvision.eu>,
Vignesh Raghavendra <vigneshr@ti.com>,
Sekhar Nori <nsekhar@ti.com>
Subject: Re: [PATCH RFC 1/2] Documentation: devicetree: Add property for ignoring the dummy bits sent before read transfer
Date: Thu, 10 Dec 2020 21:33:18 -0600 [thread overview]
Message-ID: <20201211033301.GA3581630@robh.at.kernel.org> (raw)
In-Reply-To: <20201209175708.16252-2-a-govindraju@ti.com>
On Wed, Dec 09, 2020 at 11:27:07PM +0530, Aswath Govindraju wrote:
> Dummy zero bits are sent before data during a read transfer. This causes
> the data read to be shifted to the right. To fix this send zero bits after
> the address during a read transfer.
>
> Add property to send zero bits after the address during a read transfer.
When is this necessary? Why can't it be implied by the compatible
string which should be specific to the chip model?
>
> Suggested-by: Vignesh Raghavendra <vigneshr@ti.com>
> Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
> ---
> Documentation/devicetree/bindings/misc/eeprom-93xx46.txt | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/misc/eeprom-93xx46.txt b/Documentation/devicetree/bindings/misc/eeprom-93xx46.txt
> index a8ebb4621f79..09fb1cec54f0 100644
> --- a/Documentation/devicetree/bindings/misc/eeprom-93xx46.txt
> +++ b/Documentation/devicetree/bindings/misc/eeprom-93xx46.txt
> @@ -10,7 +10,9 @@ Optional properties:
> - read-only : parameter-less property which disables writes to the EEPROM
> - select-gpios : if present, specifies the GPIO that will be asserted prior to
> each access to the EEPROM (e.g. for SPI bus multiplexing)
> -
> +- read-op-dummy-cycles: If present specifies the number of dummy zero-bits to
> + be sent after the address during a read transfer to ignore any bits sent
> + preceding the data.
> Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt
> apply. In particular, "reg" and "spi-max-frequency" properties must be given.
>
> --
> 2.17.1
>
next prev parent reply other threads:[~2020-12-11 3:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 17:57 [PATCH RFC 0/2] eeprom: eeprom_93xx46: Add support for sending zero bits after address during read transfer Aswath Govindraju
2020-12-09 17:57 ` [PATCH RFC 1/2] Documentation: devicetree: Add property for ignoring the dummy bits sent before " Aswath Govindraju
2020-12-11 3:33 ` Rob Herring [this message]
2020-12-11 15:04 ` Aswath Govindraju
2020-12-14 22:23 ` Rob Herring
2020-12-15 16:12 ` Aswath Govindraju
2020-12-17 13:48 ` Aswath Govindraju
2020-12-17 15:48 ` Rob Herring
2020-12-17 16:02 ` Aswath Govindraju
2020-12-09 17:57 ` [PATCH RFC 2/2] eeprom: eeprom_93xx46: Add support for ignoring the dummy bit preceding data during " Aswath Govindraju
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