From mboxrd@z Thu Jan 1 00:00:00 1970 From: alexandre.belloni@free-electrons.com (Alexandre Belloni) Date: Fri, 19 Sep 2014 11:50:01 +0200 Subject: [PATCH v4 4/7] ARM: l2c: Add support for overriding prefetch settings In-Reply-To: <1409062680-15906-5-git-send-email-t.figa@samsung.com> References: <1409062680-15906-1-git-send-email-t.figa@samsung.com> <1409062680-15906-5-git-send-email-t.figa@samsung.com> Message-ID: <20140919095000.GF29620@piout.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 26/08/2014 at 16:17:57 +0200, Tomasz Figa wrote : > Firmware on certain boards (e.g. ODROID-U3) can leave incorrect L2C prefetch > settings configured in registers leading to crashes if L2C is enabled > without overriding them. This patch introduces bindings to enable > prefetch settings to be specified from DT and necessary support in the > driver. > > Signed-off-by: Tomasz Figa Tested-by: Alexandre Belloni It is working and useful on Atmel's sama5d4 were the bootloader is not configuring the L2C prefetch. However, I'm wondering whether we should add support for setting L310_PREFETCH_CTRL_DATA_PREFETCH and L310_PREFETCH_CTRL_INSTR_PREFETCH. I'm currently doing it by using ".l2c_aux_val = L310_AUX_CTRL_DATA_PREFETCH | L310_AUX_CTRL_INSTR_PREFETCH" (those are the same bits) but this has the disadvantage of displaying the "L2C: platform modifies aux control register:" twice. > + if (!of_property_read_u32(np, "arm,prefetch-offset", &val)) { > + prefetch &= ~L310_PREFETCH_CTRL_OFFSET_MASK; > + prefetch |= val & L310_PREFETCH_CTRL_OFFSET_MASK; > + } > + While you use val directly here, later, while printing the offset, val + 1 is used. Maybe it would be better to have the same number in both places, else you end up with having "arm,prefetch-offset = <1>" in your DT and the kernel printing "L2C-310 ID prefetch enabled, offset 2 lines". -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com