From: Michal Suchanek <hramrach@gmail.com>
To: "R, Vignesh" <vigneshr@ti.com>
Cc: Mark Brown <broonie@kernel.org>,
devicetree <devicetree@vger.kernel.org>,
Brian Norris <computersforpeace@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
Tony Lindgren <tony@atomide.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
Huang Shijie <b32955@freescale.com>,
MTD Maling List <linux-mtd@lists.infradead.org>,
linux-omap@vger.kernel.org, David Woodhouse <dwmw2@infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 1/5] spi: introduce flag for memory mapped read
Date: Wed, 5 Aug 2015 07:21:00 +0200 [thread overview]
Message-ID: <CAOMqctThys1C3vw7u8UU6iX8c9EDCWowaWg5F1O3i3X-w7KQhA@mail.gmail.com> (raw)
In-Reply-To: <55C0FD98.1090107@ti.com>
Hello,
On 4 August 2015 at 19:59, R, Vignesh <vigneshr@ti.com> wrote:
>
>
> On 8/4/2015 9:21 PM, Mark Brown wrote:
>> On Mon, Aug 03, 2015 at 10:27:19AM +0530, Vignesh R wrote:
>>
>>> @use_mmap_mode: Some SPI controller chips are optimized for interacting
>>> with serial flash memories. These chips have memory mapped interface,
>>> through which entire serial flash memory slave can be read/written as if
>>> though they are physical memories (like RAM). Using this interface,
>>> flash can be accessed using memcpy() function and the spi controller
>>> hardware will take care of communicating with serial flash over SPI.
>>> Setting this flag will indicate the SPI controller driver that the
>>> spi_message is from mtd layer to read from/write to flash. The SPI
>>> master driver can then appropriately switch the controller to memory
>>> mapped interface to read from/write to flash, based on this flag (See
>>> drivers/spi/spi-ti-qspi.c for example).
>>> NOTE: If the SPI controller chip lacks memory mapped interface, then the
>>> driver will ignore this flag and use normal SPI protocol to read
>>> from/write to flash. Communication with non-flash SPI devices is not
>>> possible using the memory mapped interface.
>>
>> I still can't tell from the above what this interface is supposed to do.
>> It sounds like the use of memory mapped mode is supposed to be
>> transparent to users, it should just affect how the controller interacts
>> with the hardware, but if that's the case why do we need to expose it to
>> users at all? Shouldn't the driver just use memory mapped mode if it's
>> faster?
>>
>
> TI QSPI controller has two blocks:
> 1. SPI_CORE: This is generic(normal) spi mode. This can be used to
> communicate with any SPI devices (serial flashes as well as non-flash
> devices like touchscreen).
> 2. SFI_MM_IF(SPI memory mapped interface): The SFI_MM_IF block only
> allows reading and writing to an SPI flash device only. Used to speed up
> flash reads. It _cannot_ be used to communicate with non flash devices.
> Now, the spi_message that ti-qspi receives in transfer_one() callback
> can be from mtd device(in which case SFI_MM_IF can be used) or from any
> other non flash SPI device (in which case SFI_MM_IF must not be used
> instead SPI_CORE is to be used) but there is no way(is there?) to
> distinguish where spi_message is from. Therefore I introduced flag
> (use_mmap_mode) to struct spi_message. mtd driver will set flag to true,
> this helps the ti-qspi driver to determine that the user is flash device
> and thus can do read via SFI_MM_IF. If this flag is not set then the
> user is assumed to be non flash SPI driver and will use SPI_CORE block
> to communicate.
>
> On the whole, I just need a way to determine that the user is a flash
> device in order to switch to memory mapped interface.
>
Maybe it can be set on the SPI slave rather than each message.
Thanks
Michal
WARNING: multiple messages have this Message-ID (diff)
From: Michal Suchanek <hramrach-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: "R, Vignesh" <vigneshr-l0cyMroinI0@public.gmane.org>
Cc: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Brian Norris
<computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>,
Linux Kernel Mailing List
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-spi <linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Huang Shijie <b32955-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
MTD Maling List
<linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [RFC PATCH 1/5] spi: introduce flag for memory mapped read
Date: Wed, 5 Aug 2015 07:21:00 +0200 [thread overview]
Message-ID: <CAOMqctThys1C3vw7u8UU6iX8c9EDCWowaWg5F1O3i3X-w7KQhA@mail.gmail.com> (raw)
In-Reply-To: <55C0FD98.1090107-l0cyMroinI0@public.gmane.org>
Hello,
On 4 August 2015 at 19:59, R, Vignesh <vigneshr-l0cyMroinI0@public.gmane.org> wrote:
>
>
> On 8/4/2015 9:21 PM, Mark Brown wrote:
>> On Mon, Aug 03, 2015 at 10:27:19AM +0530, Vignesh R wrote:
>>
>>> @use_mmap_mode: Some SPI controller chips are optimized for interacting
>>> with serial flash memories. These chips have memory mapped interface,
>>> through which entire serial flash memory slave can be read/written as if
>>> though they are physical memories (like RAM). Using this interface,
>>> flash can be accessed using memcpy() function and the spi controller
>>> hardware will take care of communicating with serial flash over SPI.
>>> Setting this flag will indicate the SPI controller driver that the
>>> spi_message is from mtd layer to read from/write to flash. The SPI
>>> master driver can then appropriately switch the controller to memory
>>> mapped interface to read from/write to flash, based on this flag (See
>>> drivers/spi/spi-ti-qspi.c for example).
>>> NOTE: If the SPI controller chip lacks memory mapped interface, then the
>>> driver will ignore this flag and use normal SPI protocol to read
>>> from/write to flash. Communication with non-flash SPI devices is not
>>> possible using the memory mapped interface.
>>
>> I still can't tell from the above what this interface is supposed to do.
>> It sounds like the use of memory mapped mode is supposed to be
>> transparent to users, it should just affect how the controller interacts
>> with the hardware, but if that's the case why do we need to expose it to
>> users at all? Shouldn't the driver just use memory mapped mode if it's
>> faster?
>>
>
> TI QSPI controller has two blocks:
> 1. SPI_CORE: This is generic(normal) spi mode. This can be used to
> communicate with any SPI devices (serial flashes as well as non-flash
> devices like touchscreen).
> 2. SFI_MM_IF(SPI memory mapped interface): The SFI_MM_IF block only
> allows reading and writing to an SPI flash device only. Used to speed up
> flash reads. It _cannot_ be used to communicate with non flash devices.
> Now, the spi_message that ti-qspi receives in transfer_one() callback
> can be from mtd device(in which case SFI_MM_IF can be used) or from any
> other non flash SPI device (in which case SFI_MM_IF must not be used
> instead SPI_CORE is to be used) but there is no way(is there?) to
> distinguish where spi_message is from. Therefore I introduced flag
> (use_mmap_mode) to struct spi_message. mtd driver will set flag to true,
> this helps the ti-qspi driver to determine that the user is flash device
> and thus can do read via SFI_MM_IF. If this flag is not set then the
> user is assumed to be non flash SPI driver and will use SPI_CORE block
> to communicate.
>
> On the whole, I just need a way to determine that the user is a flash
> device in order to switch to memory mapped interface.
>
Maybe it can be set on the SPI slave rather than each message.
Thanks
Michal
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WARNING: multiple messages have this Message-ID (diff)
From: hramrach@gmail.com (Michal Suchanek)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 1/5] spi: introduce flag for memory mapped read
Date: Wed, 5 Aug 2015 07:21:00 +0200 [thread overview]
Message-ID: <CAOMqctThys1C3vw7u8UU6iX8c9EDCWowaWg5F1O3i3X-w7KQhA@mail.gmail.com> (raw)
In-Reply-To: <55C0FD98.1090107@ti.com>
Hello,
On 4 August 2015 at 19:59, R, Vignesh <vigneshr@ti.com> wrote:
>
>
> On 8/4/2015 9:21 PM, Mark Brown wrote:
>> On Mon, Aug 03, 2015 at 10:27:19AM +0530, Vignesh R wrote:
>>
>>> @use_mmap_mode: Some SPI controller chips are optimized for interacting
>>> with serial flash memories. These chips have memory mapped interface,
>>> through which entire serial flash memory slave can be read/written as if
>>> though they are physical memories (like RAM). Using this interface,
>>> flash can be accessed using memcpy() function and the spi controller
>>> hardware will take care of communicating with serial flash over SPI.
>>> Setting this flag will indicate the SPI controller driver that the
>>> spi_message is from mtd layer to read from/write to flash. The SPI
>>> master driver can then appropriately switch the controller to memory
>>> mapped interface to read from/write to flash, based on this flag (See
>>> drivers/spi/spi-ti-qspi.c for example).
>>> NOTE: If the SPI controller chip lacks memory mapped interface, then the
>>> driver will ignore this flag and use normal SPI protocol to read
>>> from/write to flash. Communication with non-flash SPI devices is not
>>> possible using the memory mapped interface.
>>
>> I still can't tell from the above what this interface is supposed to do.
>> It sounds like the use of memory mapped mode is supposed to be
>> transparent to users, it should just affect how the controller interacts
>> with the hardware, but if that's the case why do we need to expose it to
>> users at all? Shouldn't the driver just use memory mapped mode if it's
>> faster?
>>
>
> TI QSPI controller has two blocks:
> 1. SPI_CORE: This is generic(normal) spi mode. This can be used to
> communicate with any SPI devices (serial flashes as well as non-flash
> devices like touchscreen).
> 2. SFI_MM_IF(SPI memory mapped interface): The SFI_MM_IF block only
> allows reading and writing to an SPI flash device only. Used to speed up
> flash reads. It _cannot_ be used to communicate with non flash devices.
> Now, the spi_message that ti-qspi receives in transfer_one() callback
> can be from mtd device(in which case SFI_MM_IF can be used) or from any
> other non flash SPI device (in which case SFI_MM_IF must not be used
> instead SPI_CORE is to be used) but there is no way(is there?) to
> distinguish where spi_message is from. Therefore I introduced flag
> (use_mmap_mode) to struct spi_message. mtd driver will set flag to true,
> this helps the ti-qspi driver to determine that the user is flash device
> and thus can do read via SFI_MM_IF. If this flag is not set then the
> user is assumed to be non flash SPI driver and will use SPI_CORE block
> to communicate.
>
> On the whole, I just need a way to determine that the user is a flash
> device in order to switch to memory mapped interface.
>
Maybe it can be set on the SPI slave rather than each message.
Thanks
Michal
next prev parent reply other threads:[~2015-08-05 5:21 UTC|newest]
Thread overview: 150+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 8:41 [RFC PATCH 0/5] Add memory mapped read support for TI QSPI Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` [RFC PATCH 1/5] spi: introduce flag for memory mapped read Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-31 18:17 ` Mark Brown
2015-07-31 18:17 ` Mark Brown
2015-07-31 18:17 ` Mark Brown
2015-08-03 4:57 ` Vignesh R
2015-08-03 4:57 ` Vignesh R
2015-08-03 4:57 ` Vignesh R
2015-08-04 15:51 ` Mark Brown
2015-08-04 15:51 ` Mark Brown
2015-08-04 17:59 ` R, Vignesh
2015-08-04 17:59 ` R, Vignesh
2015-08-04 17:59 ` R, Vignesh
2015-08-04 17:59 ` R, Vignesh
2015-08-05 5:21 ` Michal Suchanek [this message]
2015-08-05 5:21 ` Michal Suchanek
2015-08-05 5:21 ` Michal Suchanek
2015-08-05 5:21 ` Michal Suchanek
2015-08-05 5:35 ` Vignesh R
2015-08-05 5:35 ` Vignesh R
2015-08-05 5:35 ` Vignesh R
2015-08-05 5:35 ` Vignesh R
2015-08-05 5:57 ` Michal Suchanek
2015-08-05 5:57 ` Michal Suchanek
2015-08-05 5:57 ` Michal Suchanek
2015-08-05 5:57 ` Michal Suchanek
2015-08-05 11:50 ` Mark Brown
2015-08-05 11:50 ` Mark Brown
2015-08-05 12:40 ` Michal Suchanek
2015-08-05 12:40 ` Michal Suchanek
2015-08-05 12:40 ` Michal Suchanek
2015-08-05 12:40 ` Michal Suchanek
2015-08-05 12:44 ` Mark Brown
2015-08-05 12:44 ` Mark Brown
2015-08-05 12:44 ` Mark Brown
2015-08-05 12:44 ` Mark Brown
2015-08-05 12:56 ` Michal Suchanek
2015-08-05 12:56 ` Michal Suchanek
2015-08-05 12:56 ` Michal Suchanek
2015-08-06 9:02 ` Mark Brown
2015-08-06 9:02 ` Mark Brown
2015-08-06 9:02 ` Mark Brown
2015-08-06 10:01 ` Michal Suchanek
2015-08-06 10:01 ` Michal Suchanek
2015-08-06 10:01 ` Michal Suchanek
2015-08-06 10:22 ` Russell King - ARM Linux
2015-08-06 10:22 ` Russell King - ARM Linux
2015-08-06 10:22 ` Russell King - ARM Linux
2015-08-06 10:22 ` Russell King - ARM Linux
2015-08-06 11:00 ` Mark Brown
2015-08-06 11:00 ` Mark Brown
2015-08-06 11:00 ` Mark Brown
2015-08-06 11:02 ` Michal Suchanek
2015-08-06 11:02 ` Michal Suchanek
2015-08-06 11:02 ` Michal Suchanek
2015-08-06 11:02 ` Michal Suchanek
2015-08-06 12:25 ` Vignesh R
2015-08-06 12:25 ` Vignesh R
2015-08-06 12:25 ` Vignesh R
2015-08-06 12:25 ` Vignesh R
2015-08-06 12:25 ` Vignesh R
2015-08-06 13:51 ` Russell King - ARM Linux
2015-08-06 13:51 ` Russell King - ARM Linux
2015-08-06 13:51 ` Russell King - ARM Linux
2015-08-06 16:14 ` Geert Uytterhoeven
2015-08-06 16:14 ` Geert Uytterhoeven
2015-08-06 16:14 ` Geert Uytterhoeven
2015-08-06 16:14 ` Geert Uytterhoeven
2015-08-06 18:20 ` Michal Suchanek
2015-08-06 18:20 ` Michal Suchanek
2015-08-06 18:20 ` Michal Suchanek
2015-08-06 18:20 ` Michal Suchanek
2015-08-06 21:33 ` Russell King - ARM Linux
2015-08-06 21:33 ` Russell King - ARM Linux
2015-08-06 21:33 ` Russell King - ARM Linux
2015-08-06 21:33 ` Russell King - ARM Linux
2015-08-07 7:38 ` Michal Suchanek
2015-08-07 7:38 ` Michal Suchanek
2015-08-07 7:38 ` Michal Suchanek
2015-08-07 7:38 ` Michal Suchanek
2015-08-07 8:35 ` Vignesh R
2015-08-07 8:35 ` Vignesh R
2015-08-07 8:35 ` Vignesh R
2015-08-07 8:25 ` Martin Sperl
2015-08-07 8:25 ` Martin Sperl
2015-08-07 8:25 ` Martin Sperl
2015-08-07 8:25 ` Martin Sperl
2015-08-07 10:16 ` Michal Suchanek
2015-08-07 10:16 ` Michal Suchanek
2015-08-07 10:16 ` Michal Suchanek
2015-08-12 9:27 ` Vignesh R
2015-08-12 9:27 ` Vignesh R
2015-08-12 9:27 ` Vignesh R
2015-08-12 9:27 ` Vignesh R
2015-08-06 16:46 ` Mark Brown
2015-08-06 16:46 ` Mark Brown
2015-08-06 16:46 ` Mark Brown
2015-08-06 16:46 ` Mark Brown
2015-08-06 18:20 ` Mark Brown
2015-08-06 18:20 ` Mark Brown
2015-08-06 18:20 ` Mark Brown
2015-08-06 11:23 ` Mark Brown
2015-08-06 11:23 ` Mark Brown
2015-08-06 11:23 ` Mark Brown
2015-08-06 11:23 ` Mark Brown
2015-08-06 11:42 ` Michal Suchanek
2015-08-06 11:42 ` Michal Suchanek
2015-08-06 11:42 ` Michal Suchanek
2015-08-06 16:03 ` Mark Brown
2015-08-06 16:03 ` Mark Brown
2015-08-06 16:03 ` Mark Brown
2015-07-28 8:41 ` [RFC PATCH 2/5] spi: spi-ti-qspi: Add memory mapped read support Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` [RFC PATCH 3/5] mtd: devices: m25p80: set flag to request memory mapped read Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` [RFC PATCH 4/5] ARM: dts: DRA7: Add memory map region entries for qspi Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-31 13:48 ` Sekhar Nori
2015-07-31 13:48 ` Sekhar Nori
2015-07-31 13:48 ` Sekhar Nori
2015-08-03 5:09 ` Vignesh R
2015-08-03 5:09 ` Vignesh R
2015-08-03 5:09 ` Vignesh R
2015-08-03 5:09 ` Vignesh R
2015-07-31 18:19 ` Mark Brown
2015-07-31 18:19 ` Mark Brown
2015-07-31 18:19 ` Mark Brown
2015-08-03 5:02 ` Vignesh R
2015-08-03 5:02 ` Vignesh R
2015-08-03 5:02 ` Vignesh R
2015-08-03 5:02 ` Vignesh R
2015-08-04 15:52 ` Mark Brown
2015-08-04 15:52 ` Mark Brown
2015-08-04 15:52 ` Mark Brown
2015-07-31 21:28 ` Brian Norris
2015-07-31 21:28 ` Brian Norris
2015-08-03 5:06 ` Vignesh R
2015-08-03 5:06 ` Vignesh R
2015-08-03 5:06 ` Vignesh R
2015-08-03 5:06 ` Vignesh R
2015-07-28 8:41 ` [RFC PATCH 5/5] ARM: dts: AM4372: " Vignesh R
2015-07-28 8:41 ` Vignesh R
2015-07-28 8:41 ` Vignesh R
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