Messages in this thread | | | Date | Thu, 14 Jul 2022 23:51:56 +0200 | From | Michael Walle <> | Subject | Re: [PATCH 1/2] mtd: spi-nor: When a flash memory is missing do not report an error |
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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
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