Hi Hans, On Thu, 5 Apr 2018 16:08:24 +0200 Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > On 05-04-18 16:00, Hans de Goede wrote: > > Hi, > > > On 05-04-18 15:54, Thierry Reding wrote: > >> On Thu, Apr 05, 2018 at 03:27:03PM +0200, Hans de Goede wrote: > >>> Hi, > >>> > >>> 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. > >>> > >>> 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. > >> > >> Agreed, although I prefer such helpers to be opt-in, rather than > >> opt-out. In my experience that tends make the helpers more resilient to > >> this kind of regression. It also simplifies things because instead of > >> drivers saying "I want all the helpers except this one and that one", > >> they can simply say "I want these helpers and that one". In the former > >> case whenever you add some new (opt-out) feature, you have to update all > >> drivers and add the exception. In the latter you only need to extend the > >> drivers that want to make use of the new helper. > > Erm, the idea never was to make this opt-out but rather opt in, so > we add a flags parameter to ahci_platform_get_resources() and all > current users pass in 0 for that to keep the current behavior. > > And only the generic drivers/ata/ahci_platform.c driver will pass > in a the new AHCI_PLATFORM_GET_RESETS flag, which makes > ahci_platform_get_resources() (and the other functions) also deal > with resets. > > >> With that in mind, rather than adding a flag to the > >> ahci_platform_get_resources() function, it might be more flexible to > >> split the helpers into finer-grained functions. That way drivers can > >> pick whatever functionality they want from the helpers. > > > Good point, so lets: > > > 1) Revert the patch for now > > 2) Have a new version of the patch which adds a ahci_platform_get_resets() helper > > 3) Modify the generic drivers/ata/ahci_platform.c driver to call the new > > ?? ahci_platform_get_resets() between its ahci_platform_get_resources() > > ?? and ahci_platform_enable_resources() calls. > > ?? I think that ahci_platform_enable_resources() should still automatically > > ?? do the right thing wrt resets if ahci_platform_get_resets() was called > > ?? (otherwise the resets array will be empty and should be skipped) > > > This should make the generic driver usable for the UniPhier SoCs and > > maybe some other drivers like the ahci_st driver can also switch to the > > new ahci_platform_get_resets() functionality to reduce their code a bit. > > So thinking slightly longer about this, with the opt-in variant > (which is what I intended all along) I do think that a flags parameter > is better, because the whole idea behind lib_ahci_platform is to avoid > having to do err = get_resource_a(), if (err) bail, err = get_resource_b() > if (err) bail, etc. in all the ahci (platform) drivers. And having fine > grained helpers re-introduces that. In case of adding a flag instead of get_resource_a(), for example, we add the flag for use of resets, -struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev) +struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev, + bool use_reset) and for now all the drivers using this function need to add the argument as false to the caller. - hpriv = ahci_platform_get_resources(pdev); + hpriv = ahci_platform_get_resources(pdev, false); Surely this can avoid adding functions such get_resource_a(). If we apply another feature later, we add its flag as one of the arguments instead. Is it right? Thank you, --- Best Regards, Kunihiko Hayashi -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
