From: <Tudor.Ambarus@microchip.com>
To: <roman@advem.lv>, <linux-mtd@lists.infradead.org>
Cc: marek.vasut@gmail.com
Subject: Re: [PATCH 1/2] mtd: spi-nor: fix GigaDevice quad_enable
Date: Sun, 28 Jul 2019 06:21:37 +0000 [thread overview]
Message-ID: <c80dc6d3-d9de-7e95-f1e0-62dea07ef923@microchip.com> (raw)
In-Reply-To: <11718527-0145-a99d-83fe-19885c9609f0@microchip.com>
On 07/28/2019 08:48 AM, Tudor.Ambarus@microchip.com wrote:
> External E-Mail
>
>
> Hi, Roman,
>
> On 07/27/2019 12:08 AM, Roman Yeryomin wrote:
>> External E-Mail
>>
>>
>> According to datasheets all GD devices are capable of quad mode, which
>
> Does any of these flashes implement the Basic Flash Parameter Table? Can't we
> determine the QE Requirements by parsing BFPT?
GD25Q256D can retrieve the QE requirements from BFPT dword 15. No need to set
the quad_enable pointer when declaring this flash, it will be overwritten when
parsing BFPT.
GD25Q256C implements JESD216A - just the first 9 dwords of BFPT, and it can't
determine the QE Requirements by parsing the BFPT. That's way we explicitly set
the quad_enable function pointer at flash declaration.
>
>> is enabled via Status Register-2, bit 1 (S9). This corresponds to
>> Spansion SR/CR operations. Unfortunately only gd25q256 datasheet is
>> clear about Quad Enable Requirements (QER), others have no such
>> information in datasheets.
>> So define quad_enable for all GD devices to be sure.
>
> Which flash did you test?
What you can do is to check which of these flashes can't determine the QE
requirements by parsing BFPT and set the quad_enable just for those who can't.
And it would be preferable to do this just for the flashes that you can test.
>
> Cheers,
> ta
>
>> Also gd25q256 is an exception. There are two versions: C and D.
>> First one uses S6 bit (like described in e27072851bf7d) but the latter
>> uses S9 bit like others. To add support for D this should be handled
>> differently, so, to retain compatibility, leave gd25q256 quad_enable
>> callback intact.
>>
>> Signed-off-by: Roman Yeryomin <roman@advem.lv>
>> ---
>> drivers/mtd/spi-nor/spi-nor.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
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next prev parent reply other threads:[~2019-07-28 6:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 21:08 [PATCH 1/2] mtd: spi-nor: fix GigaDevice quad_enable Roman Yeryomin
2019-07-28 5:48 ` Tudor.Ambarus
2019-07-28 6:21 ` Tudor.Ambarus [this message]
2019-08-07 20:10 ` Roman Yeryomin
2019-07-28 8:47 ` Sergei Shtylyov
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