From: Ulf Hansson <ulf.hansson@linaro.org>
To: Michal Simek <michal.simek@xilinx.com>
Cc: Manish Narani <manish.narani@xilinx.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Adrian Hunter <adrian.hunter@intel.com>,
rajan.vaja@xilinx.com, jolly.shah@xilinx.com,
nava.manne@xilinx.com, Olof Johansson <olof@lixom.net>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 3/3] mmc: sdhci-of-arasan: Add support for ZynqMP Platform Tap Delays Setup
Date: Mon, 17 Jun 2019 16:58:47 +0200 [thread overview]
Message-ID: <CAPDyKFp6O8rPZDZS4iKJam2+tXeen_ZMOXKw=WVzJNpBXcSc9g@mail.gmail.com> (raw)
In-Reply-To: <948514a0-e310-75fd-e8a8-6ef8bb14e41f@xilinx.com>
[...]
> >>
> >>
> >>> In regards to the mmc data part, I suggest to drop the
> >>> ->set_tap_delay() callback, but rather use a boolean flag to indicate
> >>> whether clock phases needs to be changed for the variant. Potentially
> >>> that could even be skipped and instead call clk_set_phase()
> >>> unconditionally, as the clock core deals fine with clock providers
> >>> that doesn't support the ->set_phase() callback.
> >>
> >> In connection to another version of this driver for latest Xilinx chip
> >> it would be better to keep set_tap_delay callback in the driver. The
> >> reason is that new chip/ip is capable to setup tap delays directly
> >> without asking firmware to do it. That's why for versal IP there is a
> >> need to call different setup_tap_delay function.
> >
> > The ->set_tap_delay() callback is for ZyncMp pointing to
> > sdhci_arasan_zynqmp_set_tap_delay(). This function calls the
> > clk_set_phase() API.
> >
> > What does ->set_tap_delay() do for the latest version?
>
> There is different set of default tap delays which should be programmed
> and it is done just via writing to registers which are the part of
> controller address space.
Okay, I see.
Not sure what makes most sense to do here, but it sounds to me like
another ->set_phase() callback should be implemented for the clock
provider. In other words, calling clk_set_phase() should continue to
works just fine for this case as well. If it turns out to be
inconvenient, we can always add the ->set_tap_delay() at a later point
when it makes more sense.
[...]
Kind regards
Uffe
next prev parent reply other threads:[~2019-06-17 14:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 9:56 [PATCH 0/3] Add ZynqMP SD Clock Tap Delays configuration support Manish Narani
2019-06-11 9:56 ` [PATCH 1/3] firmware: xilinx: Add SDIO Tap Delay API Manish Narani
2019-06-11 9:56 ` [PATCH 2/3] dt-bindings: mmc: arasan: Document 'xlnx,zynqmp-8.9a' controller Manish Narani
2019-06-11 9:56 ` [PATCH 3/3] mmc: sdhci-of-arasan: Add support for ZynqMP Platform Tap Delays Setup Manish Narani
2019-06-13 10:36 ` Adrian Hunter
2019-06-17 11:15 ` Ulf Hansson
2019-06-17 11:27 ` Michal Simek
2019-06-17 12:21 ` Ulf Hansson
2019-06-17 14:23 ` Michal Simek
2019-06-17 14:58 ` Ulf Hansson [this message]
2019-06-18 4:59 ` Manish Narani
2019-06-19 14:40 ` Ulf Hansson
2019-06-20 8:19 ` Manish Narani
2019-06-19 8:40 ` Manish Narani
2019-06-19 13:38 ` Ulf Hansson
2019-06-20 8:14 ` Manish Narani
2019-06-20 13:33 ` Ulf Hansson
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