From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@ti.com (Kevin Hilman) Date: Wed, 16 May 2012 16:07:21 -0700 Subject: [PATCHv2 10/19] ARM: OMAP4: PM: Work-around for ROM code BUG of IVAHD/TESLA In-Reply-To: <87zk976827.fsf@ti.com> References: <1336990730-26892-1-git-send-email-t-kristo@ti.com> <1336990730-26892-11-git-send-email-t-kristo@ti.com> <87zk976827.fsf@ti.com> Message-ID: <4FB43329.50505@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/16/2012 04:05 PM, Kevin Hilman wrote: > Tero Kristo writes: > >> From: Santosh Shilimkar >> >> The ROM BUG is when MPU Domain OFF wake up sequence that can compromise >> IVA and Tesla execution. >> >> At wakeup from MPU OFF on HS device only (not GP device), when >> restoring the Secure RAM, the ROM Code reconfigures the clocks the >> same way it is done at Cold Reset. > > Ouch. > >> The IVAHD Clocks and Power Domain settings are: >> IVAHD_CM2 IVAHD_CLKCTRL_MODULE_MODE = DISABLE >> IVAHD_CM2 SL2_CLKCTRL_MODULE_MODE = DISABLE >> IVAHD_CM2 SL2_CLKSTCTRL_CLKTRCTRL = HW_AUTO >> IVAHD_PRM IVAHD_PWRSTCTRL_POWERSTATE = OFF >> The TESLA Clocks and Power Domain settings are: >> TESLA_CM1 TESLA_CLKCTRL_MODULE_MODE = DISABLE >> TESLA_CM1 TESLA_CLKSTCTRL_CLKTRCTRL = HW_AUTO >> TESLA_PRM TESLA_PWRSTCTRL_POWERSTATE = OFF >> >> This patch fixes the low power OFF mode code so that the these >> registers are saved and restore across MPU OFF state. >> >> Also because of this limitation, MPU OFF alone is not targeted without >> device OFF to avoid IVAHD and TESLA execution impact > > I don't see where this restriction is implemented. > > And, can this be hooked into cluster PM notifiers. Especially since this only effects a subset of revisions, installing the notifier only on effected revisions also removes any overhead on working revisions. Kevin