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Date: Fri, 19 Sep 2014 11:50:01 +0200 From: Alexandre Belloni <alexandre.belloni@...e-electrons.com> To: Tomasz Figa <t.figa@...sung.com> Cc: linux-samsung-soc@...r.kernel.org, Kukjin Kim <kgene.kim@...sung.com>, lauraa@...eaurora.org, tony@...mide.com, linus.walleij@...aro.org, linux-kernel@...r.kernel.org, drake@...lessm.com, loeliger@...il.com, santosh.shilimkar@...com, Russell King - ARM Linux <linux@....linux.org.uk>, linux-omap@...r.kernel.org, Tomasz Figa <tomasz.figa@...il.com>, linux-arm-kernel@...ts.infradead.org, Marek Szyprowski <m.szyprowski@...sung.com> Subject: Re: [PATCH v4 4/7] ARM: l2c: Add support for overriding prefetch settings 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 <t.figa@...sung.com> Tested-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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