On Fri, May 30, 2014 at 06:17:49PM +0200, Stephen Warren wrote: > On 05/30/2014 02:23 AM, Peter De Schrijver wrote: > > On Thu, May 29, 2014 at 09:01:27PM +0200, Stephen Warren wrote: > >> On 05/28/2014 06:54 AM, Peter De Schrijver wrote: > >>> This driver allows userspace to read the raw efuse data. Its userspace > >>> interface is modelled after the sunxi_sid driver which provides similar > >>> functionality for some Allwinner SoCs. It has been tested on > >>> Tegra20 (ventana), Tegra30 (beaverboard), Tegra114 (dalmore) and > >>> Tegra124 (jetson TK1). > >> > >>> Changes since v4: > >>> > >>> * Provide fallback to hardcoded 0x70000800 in case the apbmisc DT node is > >>> missing. This is exactly what the current code does and prevents a system > >>> crash in that case due to an invalid memory access by tegra_read_chipid() > >> > >> Wouldn't it be better to simply return an error? > > > > This would mean you can't boot a system with these patches applied unless you > > also update the device tree. The system would crash during boot because CCF > > relies on tegra_read_chipid() as an APB barrier. Also tegra_boot_secondary() > > relies on the chipid to select the correct method for booting secondary cores. > > Is this series really backwards-compatible anyway? tegra_init_fuse() > contains a whole bunch of places where resources are pulled out of DT, > and only one of those has a fallback to use APBMISC_BASE if the DT entry > isn't present. Apart from the randomness initialization, there are no users of tegra_read_straps(). tegra_fuse_readl() is a new API, so that doesn't pose any backwards-compatibility problems. The only bug I noticed when rereading the code is that tegra_get_revision() reads the fuses on an A03 Tegra20 to findout if it's A03 or A03p. This would obviously crash if the DT entries are missing. I think this can be worked around by claiming it's an A03 in case the DT entries are missing. I don't think that will cause any problems? Cheers, Peter. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
