From: Chris Brandt <Chris.Brandt@renesas.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
Mason Yang <masonccyang@mxic.com.tw>,
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Subject: RE: [PATCH 4/6] spi: Add SPIBSC driver
Date: Wed, 4 Dec 2019 22:12:57 +0000 [thread overview]
Message-ID: <TY1PR01MB1562B1CBD17676A559EBA5718A5D0@TY1PR01MB1562.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CAMuHMdVAZOa7OmT0s=RsVJsny9NujDzpdg4T+QoUXGe0kJjOTw@mail.gmail.com>
Hi Geert,
Thank you for your review and suggestions!
On Tue, Dec 3, 2019, Geert Uytterhoeven wrote:
> > +static int spibsc_wait_trans_completion(struct spibsc_priv *sbsc) {
> > + int t = 256 * 100000;
> > +
> > + while (t--) {
> > + if (spibsc_read(sbsc, CMNSR) & CMNSR_TEND)
> > + return 0;
> > + ndelay(1);
> > + }
>
> So this may busy loop for up to 25.6 ms? Oops...
>
> Can you use the interrupt (SPIHF) instead, signalling a completion?
RZ/A1 doesn't have any interrupts. And I think the interrupts in RZ/A2
only work for HyperFlash (not QSPI).
But, 25.6ms is way too long!
I'll assume the slowest clock to be 1MHz and the max FIFO transfer of 4 bytes.
That's 32us, so that's what I'll use.
> > + if (t->cs_change) {
> > + dev_err(sbsc->dev, "cs_change not supported");
> > + return -EIO;
> > + }
> > + }
>
> If you would do the checks above in .prepare_message() (like e.g. rspi
> does)...
OK, Thanks. :)
> > + case 6:
> > + dropr |= DROPR_OPD0(tx_data[5]);
> > + opde |= (1 << 0);
>
> Both checkpatch and gcc tell you to add fallthrough coments.
OK, fixed.
> ... can't you just use .transfer_one(), instead of duplicating the logic from
> spi_transfer_one_message()?
> Or is there some special detail that's not obvious to the casual reviewer?
I guess .transfer_one() could be used if I kept shoving more stuff into
.prepare_message().
But, the screwy thing about this controller is that messages that are
'Tx only' are processed differently then 'Tx then Rx' messages and not
like a traditional SPI controller.
By implementing both conditions in .spi_transfer_one_message(), it makes
that more clear for the next person in my opinion because you can see
that sometimes we have to work with the entire message as a whole, not
just individual pieces.
> > +static const struct of_device_id of_spibsc_match[] = {
> > + { .compatible = "renesas,spibsc"},
> > + { .compatible = "renesas,r7s72100-spibsc", .data = (void
> *)HAS_SPBCR},
> > + { .compatible = "renesas,r7s9210-spibsc"},
>
> Do you need to match against all 3 in the driver?
> Does SPIBSC work on RZ/A1 when not setting HAS_SPBCR?
> If not, the fallback to "renesas,spibsc" is not valid for RZ/A1.
OK, I dropped "renesas,spibsc".
I like having individual SoC names anyway.
Chris
next prev parent reply other threads:[~2019-12-04 22:13 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 3:45 [PATCH 0/6] spi: Add Renesas SPIBSC controller Chris Brandt
2019-12-03 3:45 ` [PATCH 1/6] clk: renesas: mstp: Add critical clock from device tree support Chris Brandt
2019-12-03 18:32 ` Geert Uytterhoeven
2019-12-03 18:46 ` Chris Brandt
2019-12-03 18:51 ` Geert Uytterhoeven
2019-12-03 3:45 ` [PATCH 2/6] ARM: dts: r7s72100: Add SPIBSC clocks Chris Brandt
2019-12-03 18:42 ` Geert Uytterhoeven
2019-12-03 18:57 ` Chris Brandt
2019-12-03 19:12 ` Geert Uytterhoeven
2019-12-04 8:38 ` Lee Jones
2019-12-04 9:03 ` Geert Uytterhoeven
2019-12-04 9:47 ` Lee Jones
2019-12-04 11:00 ` Chris Brandt
2019-12-03 3:45 ` [PATCH 3/6] clk: renesas: r7s9210: Add SPIBSC clock Chris Brandt
2019-12-03 18:49 ` Geert Uytterhoeven
2019-12-03 19:09 ` Chris Brandt
2019-12-03 20:40 ` Geert Uytterhoeven
2019-12-04 3:09 ` Chris Brandt
2019-12-03 3:45 ` [PATCH 4/6] spi: Add SPIBSC driver Chris Brandt
2019-12-03 14:19 ` Mark Brown
2019-12-03 15:00 ` Chris Brandt
2019-12-03 18:29 ` Geert Uytterhoeven
2019-12-04 11:25 ` Mark Brown
2019-12-04 12:14 ` Geert Uytterhoeven
2019-12-04 15:51 ` Chris Brandt
2019-12-04 16:49 ` Mark Brown
2019-12-03 18:28 ` Geert Uytterhoeven
2019-12-04 11:18 ` Mark Brown
2019-12-04 22:12 ` Chris Brandt [this message]
2019-12-03 3:45 ` [PATCH 5/6] ARM: dts: r7s9210: Add SPIBSC Device support Chris Brandt
2019-12-03 18:59 ` Geert Uytterhoeven
2019-12-03 22:38 ` Chris Brandt
2019-12-04 7:57 ` Geert Uytterhoeven
2019-12-04 11:04 ` Chris Brandt
2019-12-03 3:45 ` [PATCH 6/6] dt-bindings: spi: Document Renesas SPIBSC bindings Chris Brandt
2019-12-03 9:14 ` Sergei Shtylyov
2019-12-03 13:27 ` Chris Brandt
2019-12-03 16:04 ` Sergei Shtylyov
2019-12-03 16:35 ` Chris Brandt
2019-12-03 18:57 ` Geert Uytterhoeven
2019-12-03 20:39 ` Geert Uytterhoeven
2019-12-04 2:54 ` Chris Brandt
2019-12-04 8:56 ` Geert Uytterhoeven
2019-12-04 13:31 ` Chris Brandt
2019-12-05 15:48 ` Geert Uytterhoeven
2019-12-05 16:00 ` Chris Brandt
2019-12-04 8:40 ` Geert Uytterhoeven
2019-12-03 22:33 ` Chris Brandt
2019-12-04 8:43 ` Geert Uytterhoeven
2019-12-04 11:19 ` Chris Brandt
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