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From: Marek Vasut <marex@denx.de>
To: Heiner Kallweit <hkallweit1@gmail.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Brown <broonie@kernel.org>,
	Brian Norris <computersforpeace@gmail.com>,
	Michal Suchanek <hramrach@gmail.com>,
	MTD Maling List <linux-mtd@lists.infradead.org>,
	Cyrille Pitchen <cyrille.pitchen@atmel.com>,
	Han Xu <han.xu@nxp.com>, linux-spi <linux-spi@vger.kernel.org>
Subject: Re: [PATCH 2/2] mtd: m25p80: consider max_transfer_size when reading
Date: Tue, 07 Jun 2016 00:28:11 +0200	[thread overview]
Message-ID: <5755F8FB.2070409@denx.de> (raw)
In-Reply-To: <971ad721-5644-e5f9-2918-65db0e6b1996@gmail.com>

On 06/06/2016 11:20 PM, Heiner Kallweit wrote:
> Am 06.06.2016 um 21:46 schrieb Geert Uytterhoeven:
>> Hi Heiner,
>>
>> On Mon, Jun 6, 2016 at 8:53 PM, Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>> Am 06.06.2016 um 19:40 schrieb Mark Brown:
>>>> On Sat, Jun 04, 2016 at 12:22:37AM +0200, Heiner Kallweit wrote:
>>>>> Am 06.05.2016 um 14:14 schrieb Mark Brown:
>>>>>> Yes, it's called the maximum transfer size because it is the
>>>>>> maximum size of a transfer, not because it's the maximum size of
>>>>>> a message.
>>>>
>>>>> I'd like to come back to this discussion. You said best would be
>>>>> to fix the chip driver. To do this and calculate an appropriate
>>>>> value for max_transfer_size the chip driver would have to know that
>>>>> the spi_device is a spi-nor device.
>>>>
>>>> That doesn't make any sense, the controller hardware doesn't
>>>> magically change based on what is connected to it.
>>>>
>>> The issue with fsl-espi is that the controller deactivates CS after
>>> each physical transfer. And a lot of HW designs use the hardware CS,
>>> therefore the advise to use a GPIO instead doesn't really help.
>>
>> And you can't use pinmux to configure the pin used for hardware CS
>> to become a GPIO?
>>
> Sadly enough, no. Only the complete block of SPI signals can be switched
> to GPIO mode. But then we'd have to use bitbanging and would loose all
> features of the integrated SPI controller (FIFO's etc.)

Just for completeness, which SoC are we talking about here ?

-- 
Best regards,
Marek Vasut

WARNING: multiple messages have this Message-ID (diff)
From: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
To: Heiner Kallweit
	<hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Geert Uytterhoeven
	<geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
Cc: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Brian Norris
	<computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Michal Suchanek
	<hramrach-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	MTD Maling List
	<linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
	Cyrille Pitchen
	<cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>,
	Han Xu <han.xu-3arQi8VN3Tc@public.gmane.org>,
	linux-spi <linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH 2/2] mtd: m25p80: consider max_transfer_size when reading
Date: Tue, 07 Jun 2016 00:28:11 +0200	[thread overview]
Message-ID: <5755F8FB.2070409@denx.de> (raw)
In-Reply-To: <971ad721-5644-e5f9-2918-65db0e6b1996-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

On 06/06/2016 11:20 PM, Heiner Kallweit wrote:
> Am 06.06.2016 um 21:46 schrieb Geert Uytterhoeven:
>> Hi Heiner,
>>
>> On Mon, Jun 6, 2016 at 8:53 PM, Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>> Am 06.06.2016 um 19:40 schrieb Mark Brown:
>>>> On Sat, Jun 04, 2016 at 12:22:37AM +0200, Heiner Kallweit wrote:
>>>>> Am 06.05.2016 um 14:14 schrieb Mark Brown:
>>>>>> Yes, it's called the maximum transfer size because it is the
>>>>>> maximum size of a transfer, not because it's the maximum size of
>>>>>> a message.
>>>>
>>>>> I'd like to come back to this discussion. You said best would be
>>>>> to fix the chip driver. To do this and calculate an appropriate
>>>>> value for max_transfer_size the chip driver would have to know that
>>>>> the spi_device is a spi-nor device.
>>>>
>>>> That doesn't make any sense, the controller hardware doesn't
>>>> magically change based on what is connected to it.
>>>>
>>> The issue with fsl-espi is that the controller deactivates CS after
>>> each physical transfer. And a lot of HW designs use the hardware CS,
>>> therefore the advise to use a GPIO instead doesn't really help.
>>
>> And you can't use pinmux to configure the pin used for hardware CS
>> to become a GPIO?
>>
> Sadly enough, no. Only the complete block of SPI signals can be switched
> to GPIO mode. But then we'd have to use bitbanging and would loose all
> features of the integrated SPI controller (FIFO's etc.)

Just for completeness, which SoC are we talking about here ?

-- 
Best regards,
Marek Vasut
--
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  reply	other threads:[~2016-06-06 22:28 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-27 22:50 [PATCH 2/2] mtd: m25p80: consider max_transfer_size when reading Heiner Kallweit
2016-04-05 19:39 ` Brian Norris
2016-04-05 20:08   ` Heiner Kallweit
2016-04-05 21:07     ` Brian Norris
2016-04-07 19:09       ` Heiner Kallweit
2016-05-05 23:57         ` Brian Norris
2016-05-05 23:57           ` Brian Norris
2016-05-06 12:14           ` Mark Brown
2016-05-06 12:14             ` Mark Brown
2016-06-03 22:22             ` Heiner Kallweit
2016-06-03 22:22               ` Heiner Kallweit
2016-06-06 17:40               ` Mark Brown
2016-06-06 17:40                 ` Mark Brown
2016-06-06 18:28                 ` Brian Norris
2016-06-06 18:28                   ` Brian Norris
2016-06-06 18:34                   ` Mark Brown
2016-06-06 18:34                     ` Mark Brown
2016-06-06 18:43                     ` Brian Norris
2016-06-06 18:43                       ` Brian Norris
2016-06-06 18:48                       ` Mark Brown
2016-06-06 18:48                         ` Mark Brown
2016-06-06 18:53                 ` Heiner Kallweit
2016-06-06 18:53                   ` Heiner Kallweit
2016-06-06 19:40                   ` Michal Suchanek
2016-06-06 19:40                     ` Michal Suchanek
2016-06-06 21:02                     ` Heiner Kallweit
2016-06-06 21:02                       ` Heiner Kallweit
2016-06-06 19:46                   ` Geert Uytterhoeven
2016-06-06 19:46                     ` Geert Uytterhoeven
2016-06-06 21:20                     ` Heiner Kallweit
2016-06-06 21:20                       ` Heiner Kallweit
2016-06-06 22:28                       ` Marek Vasut [this message]
2016-06-06 22:28                         ` Marek Vasut
2016-06-07  4:52                         ` Heiner Kallweit
2016-06-07  4:52                           ` Heiner Kallweit
2016-06-06 23:07                   ` Mark Brown
2016-06-06 23:07                     ` Mark Brown
2016-06-07  6:03                     ` Heiner Kallweit
2016-06-07  6:03                       ` Heiner Kallweit
2016-06-07  8:10                       ` Michal Suchanek
2016-06-07  8:10                         ` Michal Suchanek
2016-06-07 20:42                         ` Heiner Kallweit
2016-06-07 20:42                           ` Heiner Kallweit
2016-06-08 19:51                       ` Heiner Kallweit
2016-06-08 19:51                         ` Heiner Kallweit
2016-06-09  7:12                         ` Michal Suchanek
2016-06-09  7:12                           ` Michal Suchanek
2016-06-17 20:13                           ` Heiner Kallweit
2016-06-17 20:13                             ` Heiner Kallweit
2016-04-06 13:55   ` Cyrille Pitchen

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