Am 2022-07-14 22:55, schrieb Michal Suchánek:
On Thu, Jul 14, 2022 at 09:41:48PM +0200, Michael Walle wrote:
Hi,
Am 2022-07-14 21:19, schrieb Michal Suchanek:
> It is normal that devices are designed with multiple types of storage,
> and only some types of storage are present.
>
> The kernel can handle this situation gracefully for many types of
> storage devices such as mmc or ata but it reports and error when spi
> flash is not present.
>
> Only print a notice that the storage device is missing when no response
> to the identify command is received.
>
> Consider reply buffers with all bits set to the same value no response.
I'm not sure you can compare SPI with ATA and MMC. I'm just speaking
of
DT now, but there, for ATA and MMC you just describe the controller
and
it will auto-detect the connected storage. Whereas with SPI you
describe
Why does mmc assume storage and SDIO must be descibed? Why the special
casing?
I can't follow you here. My SDIO wireless card just works in an SD
slot and doesn't have to be described.
both the controller and the flash. So I'd argue that your hardware
description is wrong if it describes a flash which is not present.
At any rate the situation is the same - the storage may be present
sometimes. I don't think assuming some kind of device by defualt is a
sound practice.
Where is the assumption when the DT tells you there is a flash
on a specific chip select but actually there it isn't. Shouldn't
the DT then be fixed?
Maybe I don't understand your problem. What are you trying to
solve? I mean this just demotes an error to an info message.
However, when the board is designed for a specific kind of device which
is not always present, and the kernel can detect the device, it is
perfectly fine to describe it.
The alternative is to not use the device at all, even when present,
which is kind of useless.
Or let the bootloader update your device tree and disable the device
if it's not there? Or load an overlay if it is there?
-michael
