From: John Garry <john.garry@huawei.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: tudor.ambarus@microchip.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
chenxiang66@hisilicon.com, liusimin4@huawei.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>,
Jiancheng Xue <xuejiancheng@hisilicon.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 16:26:46 +0000 [thread overview]
Message-ID: <c5cfb189-797e-11c4-f77a-61ec35395b15@huawei.com> (raw)
In-Reply-To: <CAHp75Vd=TY0tPfSHMSLTh1Pgg-E7MCP5Gym1yjpLgH0Tx-2xSg@mail.gmail.com>
On 31/01/2020 15:46, Andy Shevchenko wrote:
> 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<---
>>>
Hi Andy,
>>> 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.
>
It seems that someone already had a go at that:
https://lore.kernel.org/lkml/20170317212143.bogj6efzyvvf24yd@sirena.org.uk/
Thanks,
John
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next prev parent reply other threads:[~2020-01-31 16:27 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
2020-01-31 16:26 ` John Garry [this message]
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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