Hello Markus, On 12/16/2016 06:08 AM, Markus Reichl wrote: > Am 16.12.2016 um 08:37 schrieb Krzysztof Kozlowski: >> On Thu, Dec 15, 2016 at 04:52:58PM -0800, Doug Anderson wrote: >>>> [ I added Arjun to Cc:, maybe he can help in explaining this issue >>>> (unfortunately Inderpal's email is no longer working). ] >>>> >>>> Please also note that on Exynos5422/5800 SoCs the same ARM rail >>>> voltage is used for 1.9 GHz & 2.0 GHz OPPs as for the 1.8 GHz one. >>>> IOW if the problem exists it is already present in the mainline >>>> kernel. >>> >>> Interesting. In the ChromeOS tree I see significantly higher voltages >>> needed... Note that one might naively look at >>> <https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/drivers/cpufreq/exynos5420-cpufreq.c#178>. >>> >>> 1362500, /* L0 2100 */ >>> 1312500, /* L1 2000 */ >>> >>> ..but, amazingly enough those voltages aren't used at all. Surprise! >>> >>> I believe that the above numbers are actually not used and the ASV >>> numbers are used instead. See >>> <https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/arch/arm/mach-exynos/include/mach/asv-exynos542x.h#452> >>> >>> { 2100000, >>> 1350000, 1350000, 1350000, 1350000, 1350000, >>> 1337500, 1325000, 1312500, 1300000, 1287500, >>> 1275000, 1262500, 1250000, 1237500 }, >>> >>> I believe that interpretation there is: some bins of the CPU can run >>> at 2.1 GHz just fine at 1.25 V but others need up to 1.35V. >> >> That is definitely the case. One could just look at vendors ASV table >> (for 1.9 GHz): >> { 1900000, 1300000, 1287500, 1262500, 1237500, 1225000, 1212500, >> 1200000, 1187500, 1175000, 1162500, 1150000, >> 1137500, 1125000, 1112500, 1112500}, >> >> The theoretical difference is up to 1.875V! From my experiments I saw >> BIN1 chips which should be the same... but some working on 1.2V, some on >> 1.225V (@1.9 GHz). I didn't see any requiring higher voltages but that >> does not mean that there aren't such... >> >>> ...so if you're running at 2.1 GHz at 1.25V then perhaps you're just >>> running on a CPU from a nice bin? > > I've been running the proposed frequency/voltage combinations without any > stability problems on my XU4, XU3 and even XU3-lite ( I did not delete the > nodes on XU3-lite dts) with make -j8 kernel and ssvb-cpuburn. > The chips are poorly cooled, especially the XU4 and quickly step down. > >> >> Would be nice to see a dump of PKG_ID and AUX_INFO chipid registers >> along with name of tested board. Because the "Tested on XU3" is not >> sufficient. > > If you point me to how to read these values out, I will publish them. > You can use the exynos-chipid driver posted by Pankaj. Apply patches 1 and 2 from this series (http://www.spinics.net/lists/arm-kernel/msg548384.html) and then this diff to get the values of the registers that Krzysztof asked: diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c index cf0128b18ee2..49fa76ec6d49 100644 --- a/drivers/soc/samsung/exynos-chipid.c +++ b/drivers/soc/samsung/exynos-chipid.c @@ -22,6 +22,9 @@ #define EXYNOS_MAINREV_MASK (0xF << 0) #define EXYNOS_REV_MASK (EXYNOS_SUBREV_MASK | EXYNOS_MAINREV_MASK) +#define EXYNOS_PKG_ID 0x04 +#define EXYNOS_AUX_INFO 0x1C + static const struct exynos_soc_id { const char *name; unsigned int id; @@ -71,6 +74,8 @@ int __init exynos_chipid_early_init(void) const struct of_device_id *match; u32 product_id; u32 revision; + u32 pkg_id; + u32 aux_info; np = of_find_matching_node_and_match(NULL, of_exynos_chipid_ids, &match); @@ -84,6 +89,8 @@ int __init exynos_chipid_early_init(void) product_id = readl_relaxed(exynos_chipid_base); revision = product_id & EXYNOS_REV_MASK; + pkg_id = readl_relaxed(exynos_chipid_base + EXYNOS_PKG_ID); + aux_info = readl_relaxed(exynos_chipid_base + EXYNOS_AUX_INFO); iounmap(exynos_chipid_base); soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL); @@ -100,8 +107,8 @@ int __init exynos_chipid_early_init(void) soc_dev_attr->soc_id = product_id_to_soc_id(product_id); - pr_info("Exynos: CPU[%s] CPU_REV[0x%x] Detected\n", - product_id_to_soc_id(product_id), revision); + pr_info("Exynos: CPU[%s] CPU_REV[0x%x] PKG_ID[0x%x] AUX_INFO[0x%x] \n", + product_id_to_soc_id(product_id), revision, pkg_id, aux_info); soc_dev = soc_device_register(soc_dev_attr); if (IS_ERR(soc_dev)) { Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America -- 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
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