From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suman Anna Subject: Re: [PATCH 2/6] mailbox/omap: add support for parsing dt devices Date: Tue, 8 Jul 2014 12:55:13 -0500 Message-ID: <53BC3081.9010402@ti.com> References: <1403660878-56350-1-git-send-email-s-anna@ti.com> <1403660878-56350-3-git-send-email-s-anna@ti.com> <20140628170709.GB23634@xo-6d-61-c0.localdomain> <53B18999.2020506@ti.com> <20140630185942.GA5410@amd.pavel.ucw.cz> <53B1BBA8.5090507@ti.com> <20140630203225.GA3893@amd.pavel.ucw.cz> <20140704064547.GZ28884@atomide.com> <20140704080556.GA16274@amd.pavel.ucw.cz> <20140704082354.GD28884@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140704082354.GD28884-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tony Lindgren , Pavel Machek Cc: Jassi Brar , Dave Gerlach , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Jassi Brar , Rob Herring List-Id: devicetree@vger.kernel.org Hi Tony, Pavel, On 07/04/2014 03:23 AM, Tony Lindgren wrote: > * Pavel Machek [140704 01:07]: >> Hi! >> >>>>>>>>> The non-DT support has to be maintained for now to not break >>>>>>>>> OMAP3 legacy boot, and the legacy-style code will be cleaned >>>>>>>>> up once OMAP3 is also converted to DT-boot only. >>>>>>>> >>>>>>>>> @@ -587,24 +606,157 @@ static int omap_mbox_unregister(struct omap_mbox_device *mdev) >>>>>>>>> return 0; >>>>>>>>> } >>>>>>>>> >>>>>>>>> +static const struct omap_mbox_device_data omap2_data = { >>>>>>>>> + .num_users = 4, >>>>>>>>> + .num_fifos = 6, >>>>>>>>> + .intr_type = MBOX_INTR_CFG_TYPE1, >>>>>>>>> +}; >>>>>>>>> + >>>>>>>>> +static const struct omap_mbox_device_data omap3_data = { >>>>>>>>> + .num_users = 2, >>>>>>>>> + .num_fifos = 2, >>>>>>>>> + .intr_type = MBOX_INTR_CFG_TYPE1, >>>>>>>>> +}; >>>>>>>>> + >>>>>>>>> +static const struct omap_mbox_device_data am335x_data = { >>>>>>>>> + .num_users = 4, >>>>>>>>> + .num_fifos = 8, >>>>>>>>> + .intr_type = MBOX_INTR_CFG_TYPE2, >>>>>>>>> +}; >>>>>>>> >> >>>> Aha, ok, then the intr_type should be derived from >>>> compatible-string. Or rather... you should have three >>>> compatible-strings for the three possibilities? (And then subtype, >>>> currently unused, in case there are more hw differences). >>> >>> The compatible string can and should be separate for each revision >>> unless they are the same exacat hardware revision. >> >> ACK. I checked the revision register from all SoCs. OMAP2 and OMAP3 have different revisions compared to OMAP4+. All of OMAP4, OMAP5, DRA7, AM335x and AM437x have the same version, but with different num-fifos and num-users. So, I can switch back to using omap4-mailbox for all of these SoCs only if we encode the num-fifos and num-users in DT. >> >>>>> two are HW IP design parameters, so in general putting them in DT isn't >>>>> completely a bad idea, but I will wait to see if there are any further >>>>> comments on this from Tony or DT maintainers before I make changes. >>>> >>>> Ok, right... I'd vote for putting them into DT. >>> >>> I would avoid adding custom DT properties where possible and let the >>> driver just initialize the right data based on the compatible flag. >> >> If these are HW IP design parameters, we can expect to see many >> different combinations. Yet we know ahead of time how to handle >> different parameters HW people select. That's right, the above OMAP4+ SoCs already demonstrate this behavior. >> >> Thus IMO we should do it in the device tree. > > Oh you mean from supporting new hardware with just .dts changes? > From that point of view it makes sense to have them as DT properties, > so I'm fine with that. > > Let's just try to use something that's generic like fifosize. No idea > how the property for num_fifos should be handled though as that > implies some knowledge in the driver which num_users have fifos? The fifos are not per num_users, but rather the total number of fifos within the IP block. The num_users will be the number of targets the IP block can interrupt. I tried looking for generic properties, but there weren't any that seem to fit the description. If you want generic names, I can use num-fifos and num-users, otherwise will stick to the names defined in the previous series. > > So unless that can be described clearly in a DT property as well, > the binding might be still unusable for new hardware :) > I don't expect the OMAP mailbox IP to change much in the future. There is a FIFO depth parameter as well, but that's constant in all the current versions, and even if they change it, I can already use the generic property for that. Tony, Depending on the agreement here, I may have to respin the OMAP mailbox DT/hwmod cleanup series [1] regards Suman [1] http://marc.info/?l=linux-omap&m=140365833121612&w=2 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html