From: Thierry Reding <thierry.reding@gmail.com>
To: Sowjanya Komatineni <skomatineni@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>,
jonathanh@nvidia.com, robh+dt@kernel.org,
linux-spi@vger.kernel.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v1 3/7] spi: qspi-tegra: Add support for Tegra210 QSPI controller
Date: Fri, 4 Dec 2020 13:26:14 +0100 [thread overview]
Message-ID: <X8oq5vZRD600IFwd@ulmo> (raw)
In-Reply-To: <2257bc33-80ef-a6d8-8542-480defa32937@nvidia.com>
[-- Attachment #1: Type: text/plain, Size: 1439 bytes --]
On Wed, Dec 02, 2020 at 11:17:18AM -0800, Sowjanya Komatineni wrote:
> On 12/2/20 9:27 AM, Mark Brown wrote:
> > On Tue, Dec 01, 2020 at 01:12:44PM -0800, Sowjanya Komatineni wrote:
[...]
> > > +static int tegra_qspi_setup(struct spi_device *spi)
> > > +{
> > > + if (cdata && cdata->tx_clk_tap_delay)
> > > + tx_tap = cdata->tx_clk_tap_delay;
> > > + if (cdata && cdata->rx_clk_tap_delay)
> > > + rx_tap = cdata->rx_clk_tap_delay;
> > > + tqspi->def_command2_reg = QSPI_TX_TAP_DELAY(tx_tap) |
> > > + QSPI_RX_TAP_DELAY(rx_tap);
> > > + tegra_qspi_writel(tqspi, tqspi->def_command2_reg, QSPI_COMMAND2);
> > The setup for one device shouldn't be able to affect the operation of
> > another, already running, device so either these need to be configured
> > as part of the controller probe or these configurations need to be
> > deferred until we're actually doing a transfer.
> We will only have 1 device on QSPI as we only support single chip select.
Even so we could make the driver operate as if there were multiple
devices. This has the advantage of setting a better example for someone
who might be reading this code as reference, and it might come in handy
if for whatever reason we ever end up with a QSPI controller that does
support multiple chip selects.
If that's overly complicated, maybe a compromise would be to document
very explicitly that this only works because Tegra QSPI supports a
single chip select?
Thierry
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next prev parent reply other threads:[~2020-12-04 12:27 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 21:12 [PATCH v1 0/7] Add Tegra QSPI driver Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 1/7] MAINTAINERS: Add Tegra QSPI driver section Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 2/7] dt-bindings: spi: Add Tegra QSPI device tree binding Sowjanya Komatineni
2020-12-09 17:26 ` Rob Herring
2020-12-09 20:28 ` Sowjanya Komatineni
2020-12-10 18:08 ` Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 3/7] spi: qspi-tegra: Add support for Tegra210 QSPI controller Sowjanya Komatineni
2020-12-02 0:09 ` kernel test robot
2020-12-02 17:27 ` Mark Brown
2020-12-02 19:17 ` Sowjanya Komatineni
2020-12-04 0:22 ` Sowjanya Komatineni
2020-12-04 18:52 ` Mark Brown
2020-12-04 21:04 ` Sowjanya Komatineni
2020-12-04 22:46 ` Mark Brown
2020-12-05 4:10 ` Sowjanya Komatineni
[not found] ` <70f69d4c-8a99-3893-76ea-7860eedb11fa@nvidia.com>
2020-12-08 12:00 ` Mark Brown
2020-12-04 12:26 ` Thierry Reding [this message]
2020-12-04 12:17 ` Thierry Reding
2020-12-04 12:11 ` Thierry Reding
2020-12-04 22:42 ` Sowjanya Komatineni
2020-12-04 14:41 ` Jon Hunter
2020-12-04 22:34 ` Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 4/7] spi: qspi-tegra: Add Tegra186 and Tegra194 QSPI compatibles Sowjanya Komatineni
2020-12-02 17:06 ` Mark Brown
2020-12-01 21:12 ` [PATCH v1 5/7] arm64: tegra: Enable QSPI on Jetson Nano Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 6/7] arm64: tegra: Add QSPI nodes on Tegra194 Sowjanya Komatineni
2020-12-01 21:12 ` [PATCH v1 7/7] arm64: tegra: Enable QSPI on Jetson Xavier NX Sowjanya Komatineni
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