From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Date: Mon, 26 Jan 2015 11:50:37 +0100 Subject: [U-Boot] [PATCH 1/3] ARmv7: Add a soc_init hook to start.S In-Reply-To: <20150126090913.473db570@lilith> References: <1421870607-22916-1-git-send-email-hdegoede@redhat.com> <20150122162058.GF10826@bill-the-cat> <20150126090913.473db570@lilith> Message-ID: <54C61BFD.8070901@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 26-01-15 09:09, Albert ARIBAUD wrote: > Hello Tom, > > On Thu, 22 Jan 2015 11:20:58 -0500, Tom Rini wrote: >> On Wed, Jan 21, 2015 at 09:03:25PM +0100, Hans de Goede wrote: >> >>> On some SoCs / ARMv7 CPU cores we need to do some setup before enabling the >>> icache, etc. Add a soc_init hook with a weak default which just calls >>> cpu_init_cp15. >>> >>> This way different implementations can be provided to do some extra work >>> before or after cpu_init_cp15, or completely replacing cpu_init_cp15. >>> >>> Signed-off-by: Hans de Goede >>> --- >>> arch/arm/cpu/armv7/start.S | 18 +++++++++++++++++- >>> 1 file changed, 17 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S >>> index fdc05b9..9882b20 100644 >>> --- a/arch/arm/cpu/armv7/start.S >>> +++ b/arch/arm/cpu/armv7/start.S >>> @@ -64,7 +64,7 @@ reset: >>> >>> /* the mask ROM code should have PLL and others stable */ >>> #ifndef CONFIG_SKIP_LOWLEVEL_INIT >>> - bl cpu_init_cp15 >>> + bl soc_init >>> bl cpu_init_crit >>> #endif >> >> I like the direction here. > > I don't like all of it, specifically the double call, to cpu_init_cp15 > then soc_init, for two reasons: > > 0) soc_init might touch cp15, but it's hidden in the name whereas it is > shown in cpu_init_cp15. Either both names should explicitly say they > are touching cp15, or both should not. > > 1) we cannot tell if cpu_init_cp15 should always happen before > soc_init. Having a single call to soc_init, with the understanding > that it will handle the cpu_init_cp15 call itself, makes it > possible for soc_init yo decide whether it wants to call > cpu_init_cp15 first, last or at all. There is no double call, the call to cpu_init_cp15 is being replaced with a call to soc_init, which then can call cpu_init_cp15 at any time it likes. Also see the discussion further in the thread about replacing soc_init with a call to lowlevel_init which then call s_init which may then call cpu_init_cp15 at a convenient time, the advantage of this approach is that the soc / board specific code can be written in C rather then in asm. Regards, Hans