Re: [PATCH] nvmem: core: add NVMEM_SYSFS Kconfig

From: Srinivas Kandagatla
Date: Tue Apr 16 2019 - 05:44:07 EST

On 16/04/2019 10:34, Mika Westerberg wrote:
On Tue, Apr 16, 2019 at 10:49:22AM +0530, Gaurav Kohli wrote:
Hi Srinivas,

Thanks for the patch,
By default NVMEM_SYSFS should be set true, those whose don't want they can
disable the same.

If we go with disable option, there are chances of eeprom may break in below

if (config->compat) {
rval = nvmem_sysfs_setup_compat(nvmem, config); -> this will
return error as config is disabled.
if (rval)
goto err_device_del;

I also think this may cause problems with Thunderbolt devices because
the upgradeable NVM is exposed to the userspace via these sysfs files
and those are being used by fwupd. If the files disappear it makes NVM
upgrade somewhat harder ;-)
Thanks Mika and Kohli for input.

As Kohli suggested we could make NVMEM_SYSFS default to y so that the sysfs file is available by default like before and user/board specific can decide to deselect it.

Let me know if thats Okay with you, I can spin that in v2.


At least it would be good to include following as part of this series if
you plan to disable the sysfs entries by default:

diff --git a/drivers/thunderbolt/Kconfig b/drivers/thunderbolt/Kconfig
index f4869c38c7e4..dd5facab0af2 100644
--- a/drivers/thunderbolt/Kconfig
+++ b/drivers/thunderbolt/Kconfig
@@ -7,6 +7,7 @@ menuconfig THUNDERBOLT
select CRYPTO
select NVMEM
+ select NVMEM_SYSFS
Thunderbolt Controller driver. This driver is required if you
want to hotplug Thunderbolt devices on Apple hardware or on PCs