From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rini Date: Mon, 15 Apr 2019 07:28:20 -0400 Subject: [U-Boot] [PATCH 0/6] board: ti: am43xx: Enable hardware leveling In-Reply-To: <57c9af5e-43c9-aec7-d5d7-72a923b338b2@ti.com> References: <20190412063820.25924-1-j-keerthy@ti.com> <20190413130247.GJ4664@bill-the-cat> <5274f3fd-057e-04aa-5423-96ab6b304a28@ti.com> <20190415010520.GT4664@bill-the-cat> <9cc9a21f-4864-5867-4469-318e42a9600c@ti.com> <57c9af5e-43c9-aec7-d5d7-72a923b338b2@ti.com> Message-ID: <20190415112820.GU4664@bill-the-cat> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, Apr 15, 2019 at 12:22:22PM +0300, Tero Kristo wrote: > On 15/04/2019 11:56, Keerthy wrote: > > > > > >On 15/04/19 7:43 AM, keerthy wrote: > >> > >> > >>On 4/15/2019 6:35 AM, Tom Rini wrote: > >>>On Mon, Apr 15, 2019 at 06:19:31AM +0530, keerthy wrote: > >>>> > >>>> > >>>>On 4/13/2019 6:32 PM, Tom Rini wrote: > >>>>>On Fri, Apr 12, 2019 at 12:08:14PM +0530, Keerthy wrote: > >>>>> > >>>>>>The series adds the support for hardware leveling. This needs the > >>>>>>kernel to be patched with hardware leveling support and the > >>>>>>kernel support is already in linux-next: > >>>>>> > >>>>>>https://patchwork.kernel.org/project/linux-omap/list/?series=100273 > >>>>>> > >>>>>>Match recommended values from EMIF Tools app note: > >>>>>>http://www.ti.com/lit/an/sprac70/sprac70.pdf > >>>>> > >>>>>What happens if you boot an old kernel with this series applied? > >>>>>I'm a > >>>>>bit worried about applying something that breaks existing kernels, > >>>>>thanks! > >>>> > >>>>Hi Tom, > >>>> > >>>>Deep Sleep 0 feature will fail as the corresponding hardware leveling > >>>>patches will not be present. > >>> > >>>So to be clear, some new functionality will not work, but there is no > >>>functional regression? > >> > >>Okay i got your concern. Deep sleep 0 is currently working with software > >>leveling that will stop working with this patch series(hardware > >>leveling) applied on older kernels. EMIF tools application note > >>recommends hardware leveling over what existed previously. > >> > >>Hence i posted this series. Older kernels with this patch series Deep > >>sleep 0 feature will regress. > > > >Tom, > > > >We need hardware leveling as per EMIF document. So older kernels at best > >can backport the patches here: > > > >https://patchwork.kernel.org/patch/10882123/ > >https://patchwork.kernel.org/patch/10882127/ > > > >I do not see any other way to enable hardware leveling. > > > >Tero/Dave, > > > >Any concerns? > > Well, if we are to enable the feature, I can't see how we can avoid conflict > with older kernels. However, most of the time I would say people upgrade > their kernel before upgrading u-boot so this should be fine. If we are > really worried, we could maybe add the support to kernel first, wait some > time and merge the support to u-boot after that. I assume that as the patches are working their way through -next now, we're also talking about older vendor tree kernels being where this did work? -- Tom -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: not available URL: