From: Dinh Nguyen <dinguyen@kernel.org>
To: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
robh@kernel.org, linux@armlinux.org.uk, frowand.list@gmail.com,
keescook@chromium.org, anton@enomsg.org, ccross@android.com,
tony.luck@intel.com, daniel.thompson@linaro.org,
linus.walleij@linaro.org, manivannan.sadhasivam@linaro.org,
linux-arm-kernel@lists.infradead.org, p.zabel@pengutronix.de
Subject: Re: [PATCHv5] drivers/amba: add reset control to amba bus probe
Date: Wed, 28 Aug 2019 08:34:20 -0500 [thread overview]
Message-ID: <46bcf493-9dd6-bf5b-089a-be158739a13f@kernel.org> (raw)
In-Reply-To: <30608.1566933924@turing-police>
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On 8/27/19 2:25 PM, Valdis Kl?tnieks wrote:
> On Mon, 26 Aug 2019 10:42:52 -0500, Dinh Nguyen said:
>> The primecell controller on some SoCs, i.e. SoCFPGA, is held in
>> reset by default. Until recently, the DMA controller was brought
>> out of reset by the bootloader(i.e. U-Boot). But a recent change
>> in U-Boot, the peripherals that are not used are held in reset
>> and are left to Linux to bring them out of reset.
>>
>> Add a mechanism for getting the reset property and de-assert the
>> primecell module from reset if found. This is a not a hard fail
>> if the reset properti is not present in the device tree node, so
>> the driver will continue to probe.
>
> Does this DTRT for both old and new U-Boots? My naive reading of
> this patch
What is a DTRT?
> says on an old U-Boot, we end up attempting to bring it out of
> reset even though they had already been brought out.
>
If the peripheral is already out of reset, de-asserting the reset has
no affect.
Dinh
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next prev parent reply other threads:[~2019-08-28 13:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 15:42 Dinh Nguyen
2019-08-26 15:51 ` Philipp Zabel
2019-08-27 19:25 ` Valdis Klētnieks
2019-08-28 13:34 ` Dinh Nguyen [this message]
2019-08-28 13:46 ` Valdis Klētnieks
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