Re: [PATCH] ata: ahci-platform: add reset control support
From: Patrice CHOTARD
Date: Thu Apr 05 2018 - 10:01:21 EST
On 04/05/2018 03:27 PM, Hans de Goede wrote:
> On 05-04-18 15:17, Patrice CHOTARD wrote:
>> Hi Thierry
>> On 04/05/2018 11:54 AM, Thierry Reding wrote:
>>> On Fri, Mar 23, 2018 at 10:30:53AM +0900, Kunihiko Hayashi wrote:
>>>> Add support to get and control a list of resets for the device
>>>> as optional and shared. These resets must be kept de-asserted until
>>>> the device is enabled.
>>>> This is specified as shared because some SoCs like UniPhier series
>>>> have common reset controls with all ahci controller instances.
>>>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
>>>> .../devicetree/bindings/ata/ahci-platform.txt | 1 +
>>>> drivers/ata/ahci.h | 1 +
>>>> drivers/ata/libahci_platform.c | 24
>>>> 3 files changed, 23 insertions(+), 3 deletions(-)
>>> This causes a regression on Tegra because we explicitly request the
>>> resets after the call to ahci_platform_get_resources().
>> I confirm, we got exactly the same behavior on STi platform.
>>> From a quick look, ahci_mtk and ahci_st are in the same boat,
>>> adding the
>>> corresponding maintainers to Cc.
>>> Patrice, Matthias: does SATA still work for you after this patch? This
>>> has been in linux-next since next-20180327.
>> SATA is still working after this patch, but a kernel warning is
>> triggered due to the fact that resets are both requested by
>> libahci_platform and by ahci_st driver.
> So in your case you might be able to remove the reset handling
> from the ahci_st driver and rely on the new libahci_platform
> handling instead? If that works that seems like a win to me.
Yes, I did a quick test, the reset handling can be removed from our driver.
> As said elsewhere in this thread I think it makes sense to keep (or re-add
> after a revert) the libahci_platform reset code, but make it conditional
> on a flag passed to ahci_platform_get_resources(). This way we get
> the shared code for most cases and platforms which need special handling
> can opt-out.
>>> Given how this is one of the more hardware-specific bits, perhaps a
>>> better way to do this is to move reset handling into a Uniphier driver
>>> much like Tegra, Mediatek and ST?
>>> That said, I don't see SATA support for any of the Socionext hardware
>>> either in the DT bindings or drivers/ata, so perhaps it'd be best to
>>> back this out again until we have something that's more well tested?