On Fri, Sep 19, 2014 at 08:30:07PM +0200, Alexandre Belloni wrote: > On 19/09/2014 at 17:39:32 +0100, Russell King - ARM Linux wrote : > > On Fri, Sep 19, 2014 at 11:50:01AM +0200, Alexandre Belloni wrote: > > > 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@xxxxxxxxxxx> > > > > > > Tested-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > > > > > > 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. > > > > The L2C documentation, freely available from the ARM infocentre website, > > has the answer to this for you. > > > > The two bits in the prefetch control register which control the data > > and instruction prefetching are aliases of the aux control register. > > If you set them to a value in one register, they are reflected in the > > other. > > > > The reason for that is that once the L2 cache is enabled, writes to > > the aux control register are no longer permitted, but it's safe to > > enable and disable the prefetching with the cache already enabled. > > This reason is even stated in the documentation. > > > > Yeah, so my question still holds, should we have an other way to > enable/disable I/D prefetch by adding two other DT bindings ? Your question doesn't hold, because the above answers it conclusively. No. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |