Dear Hauke Mehrtens, On Wed, 10 Jun 2015 21:26:35 +0200, Hauke Mehrtens wrote: > Thanks for asking, I did not know Russell's patch process, but Florian > guided me and now it is submitted, see > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8391/1 I tested your patch, and I'm not sure how it can work for you, because the changes made to the PREFETCH_CTRL register on the data/instruction prefetch bits are later overridden by changes made to the AUX_CTRL register. Here is what I've found so far: static void l2c_configure(void __iomem *base) { if (outer_cache.configure) { outer_cache.configure(&l2x0_saved_regs); return; } if (l2x0_data->configure) l2x0_data->configure(base); l2c_write_sec(l2x0_saved_regs.aux_ctrl, base, L2X0_AUX_CTRL); } l2x0_data->configure() is what writes the PREFETCH_CTRL register with the value determined in l2c310_of_parse() : if (revision >= L310_CACHE_ID_RTL_R2P0) { l2c_write_sec(l2x0_saved_regs.prefetch_ctrl, base, L310_PREFETCH_CTRL); } The value written in the L310_PREFETCH_CTRL register is correct: it properly has bits 28/29 sets depending on prefetch-data/prefetch-instr. However, when l2c_configure() does: l2c_write_sec(l2x0_saved_regs.aux_ctrl, base, L2X0_AUX_CTRL); It writes l2x0_saved_regs.aux_ctrl to the AUX_CTRL register, which has a "clone" of the prefetch data and prefetch instruction bits. And it resets them to zero. I've added debug messages before/after this line, and here is what I see: [ 0.000000] ==> (1) prefetch is now 0x58800000 [ 0.000000] ==> (2) prefetch is now 0x48800000 I had enabled only the prefetch-data, so in step (1) (before aux_ctrl is written to AUX_CTRL), bit 28 is correctly set to 1. However, after AUX_CTRL is written, it's restored to 0. How does your patch handles the fact that the prefetch data and prefetch instr are cloned between PREFETCH_CTRL and AUX_CTRL ? Thanks, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
