* [U-Boot] What is the expected meaning of CONFIG_SYS_NO_FLASH
@ 2015-06-10 0:02 Chris Packham
2015-06-10 7:18 ` Stefan Roese
0 siblings, 1 reply; 4+ messages in thread
From: Chris Packham @ 2015-06-10 0:02 UTC (permalink / raw
To: u-boot
Hi,
There is a bit of confusion at $dayjob about when CONFIG_SYS_NO_FLASH
is used. Initially we thought that this meant I have no parallel NOR
flash. So a board with only SPI flash would have CONFIG_SYS_NO_FLASH=1
and CONFIG_SPI_FLASH=1.
Is this understanding correct? I'd like to be able to add a blurb to
README about how CONFIG_SYS_NO_FLASH should be used. Based on what I
can tell from the code there seems to be a requirement that if
!defined(CONFIG_SYS_NO_FLASH) something must implement flash_init(),
flash_write(), etc as defined in include/flash.h. This could be a
driver like cfi_flash.c or a board specific implementation.
Thanks,
Chris
^ permalink raw reply [flat|nested] 4+ messages in thread
* [U-Boot] What is the expected meaning of CONFIG_SYS_NO_FLASH
2015-06-10 0:02 [U-Boot] What is the expected meaning of CONFIG_SYS_NO_FLASH Chris Packham
@ 2015-06-10 7:18 ` Stefan Roese
2015-06-10 10:06 ` [U-Boot] [RFC PATCH v1] README: Describe CONFIG_SYS_NO_FLASH Chris Packham
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Roese @ 2015-06-10 7:18 UTC (permalink / raw
To: u-boot
Hi Chris,
On 10.06.2015 02:02, Chris Packham wrote:
> There is a bit of confusion at $dayjob about when CONFIG_SYS_NO_FLASH
> is used. Initially we thought that this meant I have no parallel NOR
> flash. So a board with only SPI flash would have CONFIG_SYS_NO_FLASH=1
> and CONFIG_SPI_FLASH=1.
>
> Is this understanding correct?
Yes. CONFIG_SYS_NO_FLASH dates back to a time when only parallel NOR
flash (like CFI NOR) was available. And it definitely is now confusing
at least. Perhaps it would be good to rename it to
CONFIG_SYS_NO_PARALLEL_FLASH now.
> I'd like to be able to add a blurb to
> README about how CONFIG_SYS_NO_FLASH should be used.
Thanks, that would be helpful.
> Based on what I
> can tell from the code there seems to be a requirement that if
> !defined(CONFIG_SYS_NO_FLASH) something must implement flash_init(),
> flash_write(), etc as defined in include/flash.h. This could be a
> driver like cfi_flash.c or a board specific implementation.
Yes, this seems to be a correct assumption.
Thanks,
Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* [U-Boot] [RFC PATCH v1] README: Describe CONFIG_SYS_NO_FLASH
2015-06-10 7:18 ` Stefan Roese
@ 2015-06-10 10:06 ` Chris Packham
2015-06-10 13:59 ` Stefan Roese
0 siblings, 1 reply; 4+ messages in thread
From: Chris Packham @ 2015-06-10 10:06 UTC (permalink / raw
To: u-boot
Unlike most configuration options defining this actually disables
support for a feature (parallel flash). Eventually the logic behind this
should probably be flipped so that '#ifndef CONFIG_SYS_NO_FLASH' becomes
'#ifdef CONFIG_HAS_PARALLEL_FLASH' but for now lets document the
existing behaviour.
Signed-off-by: Chris Packham <judge.packham@gmail.com>
---
So this is my attempt to describe (my understanding of) how this option
should be used. Any suggestions for improvement are most welcome.
README | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/README b/README
index 3b406c2..c3fa549 100644
--- a/README
+++ b/README
@@ -3037,6 +3037,19 @@ CBFS (Coreboot Filesystem) support
this is instead controlled by the value of
/config/load-environment.
+- Parallel Flash support:
+ CONFIG_SYS_NO_FLASH
+
+ Traditionally U-boot was run on systems with parallel NOR
+ flash. This option is used to disable support for parallel NOR
+ flash. This option should be defined if the board does not have
+ parallel flash.
+
+ If this option is not defined one of the generic flash drivers
+ (e.g. CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
+ selected or the board must provide an implementation of the
+ flash API (see include/flash.h).
+
- DataFlash Support:
CONFIG_HAS_DATAFLASH
--
2.3.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [U-Boot] [RFC PATCH v1] README: Describe CONFIG_SYS_NO_FLASH
2015-06-10 10:06 ` [U-Boot] [RFC PATCH v1] README: Describe CONFIG_SYS_NO_FLASH Chris Packham
@ 2015-06-10 13:59 ` Stefan Roese
0 siblings, 0 replies; 4+ messages in thread
From: Stefan Roese @ 2015-06-10 13:59 UTC (permalink / raw
To: u-boot
On 10.06.2015 12:06, Chris Packham wrote:
> Unlike most configuration options defining this actually disables
> support for a feature (parallel flash). Eventually the logic behind this
> should probably be flipped so that '#ifndef CONFIG_SYS_NO_FLASH' becomes
> '#ifdef CONFIG_HAS_PARALLEL_FLASH'
Yes, this should be the ultimate goal. But definitely a quite complex task.
> but for now lets document the
> existing behaviour.
Ack.
> Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Thanks,
Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-06-10 13:59 UTC | newest]
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2015-06-10 0:02 [U-Boot] What is the expected meaning of CONFIG_SYS_NO_FLASH Chris Packham
2015-06-10 7:18 ` Stefan Roese
2015-06-10 10:06 ` [U-Boot] [RFC PATCH v1] README: Describe CONFIG_SYS_NO_FLASH Chris Packham
2015-06-10 13:59 ` Stefan Roese
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