From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: John Garry <john.garry@huawei.com>
Cc: Jiancheng Xue <xuejiancheng@hisilicon.com>,
chenxiang66@hisilicon.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
tudor.ambarus@microchip.com, Linuxarm <linuxarm@huawei.com>,
linux-spi <linux-spi@vger.kernel.org>,
Marek Vasut <marek.vasut@gmail.com>,
Mark Brown <broonie@kernel.org>,
"open list:MEMORY TECHNOLOGY..." <linux-mtd@lists.infradead.org>,
liusimin4@huawei.com,
Mika Westerberg <mika.westerberg@linux.intel.com>,
wanghuiqiang <wanghuiqiang@huawei.com>,
fengsheng5@huawei.com
Subject: Re: [PATCH v2 2/3] spi: Add HiSilicon v3xx SPI NOR flash controller driver
Date: Fri, 31 Jan 2020 17:46:39 +0200 [thread overview]
Message-ID: <CAHp75Vd=TY0tPfSHMSLTh1Pgg-E7MCP5Gym1yjpLgH0Tx-2xSg@mail.gmail.com> (raw)
In-Reply-To: <136bd652-dcb9-3efa-a92f-2263cbf840ad@huawei.com>
On Fri, Jan 31, 2020 at 2:03 PM John Garry <john.garry@huawei.com> wrote:
> On 31/01/2020 11:39, Andy Shevchenko wrote:
> > On Fri, Jan 31, 2020 at 12:08 PM John Garry <john.garry@huawei.com> wrote:
> >> On 13/01/2020 14:34, Andy Shevchenko wrote:
...
> >> About this topic of ACPI having no method to describe device buswidth in
> >> the resource descriptor, it may be an idea for me to raise a Tianocore
> >> feature request @ https://bugzilla.tianocore.org/
> >>
> >
> > The 19.6.126 describes the SPI resource, in particular:
> >
> > ---8<---8<---
> > DataBitLength is the size, in bits, of the smallest transfer unit for
> > this connection. _LEN is automatically
> > created to refer to this portion of the resource descriptor.
> > ---8<---8<---
> >
> > Is it what you are looking for? (As far as I know most of the
> > firmwares simple abuse this field among others)
>
> I didn't think so - I thought that there was a distinction between width
> and length in SPI terms.
My interpretation of this field is a data width of the slave.
Basically what we have as transfer->size inside SPI in the Linux
kernel.
> So how do you find that most firmwares abuse this field? AFAICS, linux
> kernel doesn't interpret this field at all.
From all tables I have this is the result of appearance (some of the
tables are like 10x times present in my data base, but nevertheless)
140 SpiSerialBusV2(0x0000,PolarityHigh,FourWireMode,0x08,
411 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x08,
1 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x08,
36 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x10,
35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x18,
35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x20,
1 SpiSerialBusV2(0x0000,PolarityLow,ThreeWireMode,0x10,
8 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x08,
1 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x10,
So, it seems I stand corrected, the field is in right use, although
cases like 0x10 and 0x20 should be carefully checked.
We may teach kernel to get something meaningful out of it.
--
With Best Regards,
Andy Shevchenko
______________________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2020-01-31 15:47 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 14:08 [PATCH v2 0/3] HiSilicon v3xx SFC driver John Garry
2019-12-09 14:08 ` [PATCH v2 1/3] mtd: spi-nor: hisi-sfc: Try to provide some clarity on which SFC we are John Garry
2020-01-16 11:03 ` Tudor.Ambarus
2019-12-09 14:08 ` [PATCH v2 2/3] spi: Add HiSilicon v3xx SPI NOR flash controller driver John Garry
2020-01-09 15:54 ` John Garry
2020-01-09 21:28 ` Mark Brown
2020-01-10 11:55 ` John Garry
2020-01-10 14:07 ` Mark Brown
2020-01-10 14:58 ` John Garry
2020-01-10 15:12 ` Mark Brown
2020-01-10 16:09 ` John Garry
2020-01-10 19:31 ` Andy Shevchenko
2020-01-13 10:09 ` John Garry
2020-01-13 11:42 ` Mark Brown
2020-01-13 13:01 ` John Garry
2020-01-13 14:06 ` Mark Brown
2020-01-13 14:17 ` Andy Shevchenko
2020-01-13 14:27 ` Mark Brown
2020-01-13 14:34 ` Andy Shevchenko
2020-01-31 10:08 ` John Garry
2020-01-31 11:39 ` Andy Shevchenko
2020-01-31 12:03 ` John Garry
2020-01-31 15:46 ` Andy Shevchenko [this message]
2020-01-31 16:26 ` John Garry
2020-02-01 11:34 ` Mark Brown
2020-02-01 11:32 ` Mark Brown
2020-01-10 19:59 ` Applied "spi: Add HiSilicon v3xx SPI NOR flash controller driver" to the spi tree Mark Brown
2019-12-09 14:08 ` [PATCH v2 3/3] MAINTAINERS: Add a maintainer for the HiSilicon v3xx SFC driver John Garry
2020-01-10 19:59 ` Applied "MAINTAINERS: Add a maintainer for the HiSilicon v3xx SFC driver" to the spi tree Mark Brown
2019-12-16 14:52 ` [PATCH v2 0/3] HiSilicon v3xx SFC driver John Garry
2019-12-16 14:56 ` Mark Brown
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