From: Ulrich Hecht <uli@fpond.eu>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Phong Hoang <phong.hoang.wz@renesas.com>
Subject: Re: [PATCH/RFC 5/6] gpio: rcar: Add support for R-Car V3U
Date: Wed, 21 Oct 2020 18:16:28 +0200 (CEST) [thread overview]
Message-ID: <739271836.305801.1603296988528@webmail.strato.com> (raw)
In-Reply-To: <CAMuHMdWovS9TDK0twf97XzNWhTmUQLCJLCYirgWPtsB9C5_Viw@mail.gmail.com>
> On 10/20/2020 10:22 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > Should input be enabled unconditionally, as recommended by the Hardware
> > Manual for backwards compatibility with existing software?
> > As per (errata?) commit ae9550f635533b1c ("gpio-rcar: Use OUTDT when
> > reading GPIOs configured as output"), the gpio-rcar driver does not use
> > the INDT register to read the status of a GPIO line when configured for
> > output.
>
> More investigation:
> 1. On SH7734, R-Car Gen1, R-Car Gen2, and RZ/G1, INDT only reflects
> the state of the input pin if the GPIO is configured for input
> (documented, verified on R-Car M2-W),
> 2. On R-Car Gen3 and RZ/G2, INDT always reflects the state of the
> input pin (documented, verified on R-Car H3/M3-W/M3-N),
> 3. On R-Car V3U, input enable can be configured explicitly through the
> new INEN register (documented, unverified).
>
> Given register accesses are slow, I think it makes sense to enable input
> explicitly and unconditionally on R-Car V3U, and always use INDT to read
> pin state on R-Car Gen3 and V3U.
That sounds like a good solution to me.
CU
Uli
next prev parent reply other threads:[~2020-10-21 16:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 12:06 [PATCH/RFC 0/6] R-Car V3U GPIO support Geert Uytterhoeven
2020-10-19 12:06 ` [PATCH/RFC 1/6] clk: renesas: r8a779a0: Remove non-existent S2 clock Geert Uytterhoeven
2020-10-21 7:37 ` Yoshihiro Shimoda
2020-12-30 16:04 ` Wolfram Sang
2020-10-19 12:06 ` [PATCH/RFC 2/6] clk: renesas: r8a779a0: Fix parent of CBFUSA clock Geert Uytterhoeven
2020-10-21 7:37 ` Yoshihiro Shimoda
2020-12-30 16:04 ` Wolfram Sang
2020-10-19 12:06 ` [PATCH/RFC 3/6] clk: renesas: r8a779a0: Add PFC/GPIO clocks Geert Uytterhoeven
2020-10-21 7:40 ` Yoshihiro Shimoda
2020-10-21 8:07 ` Yoshihiro Shimoda
2020-10-21 8:18 ` Geert Uytterhoeven
2020-12-30 16:05 ` Wolfram Sang
2020-10-19 12:06 ` [PATCH/RFC 4/6] dt-bindings: gpio: rcar: Add r8a779a0 support Geert Uytterhoeven
2020-12-30 16:05 ` Wolfram Sang
2020-10-19 12:06 ` [PATCH/RFC 5/6] gpio: rcar: Add support for R-Car V3U Geert Uytterhoeven
2020-10-20 8:22 ` Geert Uytterhoeven
2020-10-21 16:16 ` Ulrich Hecht [this message]
2020-10-21 16:15 ` Ulrich Hecht
2020-10-19 12:06 ` [PATCH/RFC 6/6] arm64: dts: r8a779a0: Add GPIO nodes Geert Uytterhoeven
2020-12-30 16:06 ` Wolfram Sang
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