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Date:   Fri, 24 Aug 2018 14:05:19 -0700
From:   vnkgutta@codeaurora.org
To:     Evan Green <evgreen@chromium.org>
Cc:     robh@kernel.org, mchehab@kernel.org, linux-edac@vger.kernel.org,
        linux-kernel@vger.kernel.org, Andy Gross <andy.gross@linaro.org>,
        David Brown <david.brown@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
        robh+dt@kernel.org, mark.rutland@arm.com,
        devicetree@vger.kernel.org, tsoni@codeaurora.org,
        ckadabi@codeaurora.org, rishabhb@codeaurora.org, bp@alien8.de
Subject: Re: [PATCH v2 3/4] drivers: edac: Add EDAC driver support for QCOM
 SoCs
In-Reply-To: <CAE=gft4ywi9+2HJVs4bjwQqo0-pMnzQzAq-WTiriLbxiPeg21g@mail.gmail.com>
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 <fc5ab365cc3808161294af4b1b2b6312@codeaurora.org>
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On 2018-08-24 13:18, Evan Green wrote:
> On Fri, Aug 24, 2018 at 11:32 AM <vnkgutta@codeaurora.org> wrote:
>> 
>> On 2018-08-23 16:04, Evan Green wrote:
>> > On Fri, Aug 17, 2018 at 5:08 PM Venkata Narendra Kumar Gutta
>> > <vnkgutta@codeaurora.org> wrote:
>> >>
>> >> From: Channagoud Kadabi <ckadabi@codeaurora.org>
>> >>
>> >> Add error reporting driver for Single Bit Errors (SBEs) and Double Bit
>> >> Errors (DBEs). As of now, this driver supports erp for Last Level
>> >> Cache
>> >> Controller (LLCC). This driver takes care of dumping registers and
>> >> adding
>> >> config options to enable and disable panic when the errors happen in
>> >> cache.
>> >>
>> >> Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>
>> >> Signed-off-by: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
>> >> Co-developed-by: Venkata Narendra Kumar Gutta
>> >> <vnkgutta@codeaurora.org>
>> >> ---
>> >>  MAINTAINERS                        |   8 +
>> >>  drivers/edac/Kconfig               |  28 +++
>> >>  drivers/edac/Makefile              |   1 +
>> >>  drivers/edac/qcom_edac.c           | 446
>> >> +++++++++++++++++++++++++++++++++++++
>> >>  include/linux/soc/qcom/llcc-qcom.h |  25 +++
>> >>  5 files changed, 508 insertions(+)
>> >>  create mode 100644 drivers/edac/qcom_edac.c
>> >>
>> >> diff --git a/MAINTAINERS b/MAINTAINERS
>> >> index 0a23427..0bff713 100644
>> >> --- a/MAINTAINERS
>> >> +++ b/MAINTAINERS
>> >> @@ -5227,6 +5227,14 @@ L:       linux-edac@vger.kernel.org
>> >>  S:     Maintained
>> >>  F:     drivers/edac/ti_edac.c
>> >>
>> >> +EDAC-QUALCOMM
>> >> +M:     Channagoud Kadabi <ckadabi@codeaurora.org>
>> >> +M:     Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
>> >> +L:     linux-arm-msm@vger.kernel.org
>> >> +L:     linux-edac@vger.kernel.org
>> >> +S:     Maintained
>> >> +F:     drivers/edac/qcom_edac.c
>> >> +
>> >>  EDIROL UA-101/UA-1000 DRIVER
>> >>  M:     Clemens Ladisch <clemens@ladisch.de>
>> >>  L:     alsa-devel@alsa-project.org (moderated for non-subscribers)
>> >> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
>> >> index 57304b2..da8f150 100644
>> >> --- a/drivers/edac/Kconfig
>> >> +++ b/drivers/edac/Kconfig
>> >> @@ -460,4 +460,32 @@ config EDAC_TI
>> >>           Support for error detection and correction on the
>> >>            TI SoCs.
>> >>
>> >> +config EDAC_QCOM
>> >> +       tristate "QCOM EDAC Controller"
>> >> +       depends on EDAC
>> >> +       help
>> >> +         Support for error detection and correction on the
>> >> +         QCOM SoCs.
>> >> +
>> >> +config EDAC_QCOM_LLCC
>> >> +       tristate "QCOM EDAC Controller for LLCC Cache"
>> >> +       depends on EDAC_QCOM && QCOM_LLCC
>> >> +       help
>> >> +         Support for error detection and correction on the
>> >> +         QCOM LLCC cache. Report errors caught by LLCC ECC
>> >> +         mechanism.
>> >> +
>> >> +         For debugging issues having to do with stability and overall
>> >> system
>> >> +          health, you should probably say 'Y' here.
>> >> +
>> >> +config EDAC_QCOM_LLCC_PANIC_ON_UE
>> >> +       bool "Panic on uncorrectable errors - qcom llcc"
>> >> +       depends on EDAC_QCOM_LLCC
>> >> +       help
>> >> +         Forcibly cause a kernel panic if an uncorrectable error (UE)
>> >> is
>> >> +         detected. This can reduce debugging times on hardware which
>> >> may be
>> >> +         operating at voltages or frequencies outside normal
>> >> specification.
>> >> +
>> >> +         For production builds, you should probably say 'N' here.
>> >> +
>> >>  endif # EDAC
>> >> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
>> >> index 02b43a7..716096d 100644
>> >> --- a/drivers/edac/Makefile
>> >> +++ b/drivers/edac/Makefile
>> >> @@ -77,3 +77,4 @@ obj-$(CONFIG_EDAC_ALTERA)             +=
>> >> altera_edac.o
>> >>  obj-$(CONFIG_EDAC_SYNOPSYS)            += synopsys_edac.o
>> >>  obj-$(CONFIG_EDAC_XGENE)               += xgene_edac.o
>> >>  obj-$(CONFIG_EDAC_TI)                  += ti_edac.o
>> >> +obj-$(CONFIG_EDAC_QCOM)                        += qcom_edac.o
>> >> diff --git a/drivers/edac/qcom_edac.c b/drivers/edac/qcom_edac.c
>> >> new file mode 100644
>> >> index 0000000..9a8c670
>> >> --- /dev/null
>> >> +++ b/drivers/edac/qcom_edac.c
>> >> @@ -0,0 +1,446 @@
>> >> +// SPDX-License-Identifier: GPL-2.0
>> >> +/*
>> >> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
>> >> + */
>> >> +
>> >> +#include <linux/edac.h>
>> >> +#include <linux/interrupt.h>
>> >> +#include <linux/kernel.h>
>> >> +#include <linux/of_device.h>
>> >> +#include <linux/platform_device.h>
>> >> +#include <linux/regmap.h>
>> >> +#include <linux/smp.h>
>> >> +#include <linux/soc/qcom/llcc-qcom.h>
>> >> +
>> >> +#include "edac_mc.h"
>> >> +#include "edac_device.h"
>> >> +
>> >> +#ifdef CONFIG_EDAC_QCOM_LLCC_PANIC_ON_UE
>> >> +#define LLCC_ERP_PANIC_ON_UE            1
>> >> +#else
>> >> +#define LLCC_ERP_PANIC_ON_UE            0
>> >> +#endif
>> >> +
>> >> +#define EDAC_LLCC                       "qcom_llcc"
>> >> +
>> >> +#define TRP_SYN_REG_CNT                 6
>> >> +
>> >> +#define DRP_SYN_REG_CNT                 8
>> >> +
>> >> +#define LLCC_COMMON_STATUS0             0x0003000C
>> >> +#define LLCC_LB_CNT_MASK                GENMASK(31, 28)
>> >> +#define LLCC_LB_CNT_SHIFT               28
>> >> +
>> >> +/* single & Double Bit syndrome register offsets */
>> >
>> > Strange capitalization going on here.
>> I'll fix this.
>> 
>> >
>> >> +#define TRP_ECC_SB_ERR_SYN0             0x0002304C
>> >> +#define TRP_ECC_DB_ERR_SYN0             0x00020370
>> >> +#define DRP_ECC_SB_ERR_SYN0             0x0004204C
>> >> +#define DRP_ECC_DB_ERR_SYN0             0x00042070
>> >
>> > I think the convention is to use lowercase hex everywhere.
>> 
>> I didn't get you. Do you mean, the Macros should be in lower case or 
>> the
>> comments?
> 
> I mean 0x0002304C should be 0x0002304c.

Oh, I see. I'll update it, Thanks.

> 
>> 
>> >
>> >> +
>> >> +/* Error register offsets */
>> >> +#define TRP_ECC_ERROR_STATUS1           0x00020348
>> >> +#define TRP_ECC_ERROR_STATUS0           0x00020344
>> >> +#define DRP_ECC_ERROR_STATUS1           0x00042048
>> >> +#define DRP_ECC_ERROR_STATUS0           0x00042044
>> >> +
>> >> +/* TRP, DRP interrupt register offsets */
>> >> +#define DRP_INTERRUPT_STATUS            0x00041000
>> >> +#define TRP_INTERRUPT_0_STATUS          0x00020480
>> >> +#define DRP_INTERRUPT_CLEAR             0x00041008
>> >> +#define DRP_ECC_ERROR_CNTR_CLEAR        0x00040004
>> >> +#define TRP_INTERRUPT_0_CLEAR           0x00020484
>> >> +#define TRP_ECC_ERROR_CNTR_CLEAR        0x00020440
>> >> +
>> >> +/* Mask and shift macros */
>> >> +#define ECC_DB_ERR_COUNT_MASK           GENMASK(4, 0)
>> >> +#define ECC_DB_ERR_WAYS_MASK            GENMASK(31, 16)
>> >> +#define ECC_DB_ERR_WAYS_SHIFT           BIT(4)
>> >> +
>> >> +#define ECC_SB_ERR_COUNT_MASK           GENMASK(23, 16)
>> >> +#define ECC_SB_ERR_COUNT_SHIFT          BIT(4)
>> >> +#define ECC_SB_ERR_WAYS_MASK            GENMASK(15, 0)
>> >> +
>> >> +#define SB_ECC_ERROR                    BIT(0)
>> >> +#define DB_ECC_ERROR                    BIT(1)
>> >> +
>> >> +#define DRP_TRP_INT_CLEAR               GENMASK(1, 0)
>> >> +#define DRP_TRP_CNT_CLEAR               GENMASK(1, 0)
>> >> +
>> >> +/* Config registers offsets*/
>> >> +#define DRP_ECC_ERROR_CFG               0x00040000
>> >> +
>> >> +/* TRP, DRP interrupt register offsets */
>> >> +#define CMN_INTERRUPT_0_ENABLE          0x0003001C
>> >> +#define CMN_INTERRUPT_2_ENABLE          0x0003003C
>> >> +#define TRP_INTERRUPT_0_ENABLE          0x00020488
>> >> +#define DRP_INTERRUPT_ENABLE            0x0004100C
>> >> +
>> >> +#define SB_ERROR_THRESHOLD              0x1
>> >> +#define SB_ERROR_THRESHOLD_SHIFT        24
>> >> +#define SB_DB_TRP_INTERRUPT_ENABLE      0x3
>> >> +#define TRP0_INTERRUPT_ENABLE           0x1
>> >> +#define DRP0_INTERRUPT_ENABLE           BIT(6)
>> >> +#define SB_DB_DRP_INTERRUPT_ENABLE      0x3
>> >> +
>> >> +enum {
>> >> +       LLCC_DRAM_CE = 0,
>> >> +       LLCC_DRAM_UE,
>> >> +       LLCC_TRAM_CE,
>> >> +       LLCC_TRAM_UE,
>> >> +       LLCC_ERR_TYPE_MAX = LLCC_TRAM_UE + 1,
>> >
>> > This is a nit, or perhaps personal preference, but I prefer to not
>> > have initializers for sentinel values, since it's one more thing
>> > someone could forget to update when adding new values.
>> 
>> I'll get rid of this, I was using this one to allocate the memory for
>> llcc_driv_data->edac_reg, (struct llcc_edac_reg_data).
>> But the suggestion was to initialize that one statically.
> 
> Sounds good.
> 
>> 
>> 
>> >
>> >> +};
>> >> +
>> >> +static int qcom_llcc_core_setup(struct regmap *llcc_bcast_regmap)
>> >> +{
>> >> +       u32 sb_err_threshold;
>> >> +       int ret;
>> >> +
>> >> +       /* Enable TRP in instance 2 of common interrupt enable
>> >> register */
>> >
>> > Can we get a comment explaining what's so special about instance 2?
>> > Instances 1 and 3 get no love?
>> 
>> I'll try to elaborate on this.
>> 
>> >
>> >> +       ret = regmap_update_bits(llcc_bcast_regmap,
>> >> CMN_INTERRUPT_2_ENABLE,
>> >> +                                TRP0_INTERRUPT_ENABLE,
>> >> +                                TRP0_INTERRUPT_ENABLE);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       /* Enable ECC interrupts on Tag Ram */
>> >> +       ret = regmap_update_bits(llcc_bcast_regmap,
>> >> TRP_INTERRUPT_0_ENABLE,
>> >> +                                SB_DB_TRP_INTERRUPT_ENABLE,
>> >> +                                SB_DB_TRP_INTERRUPT_ENABLE);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       /* Enable SB error for Data RAM */
>> >> +       sb_err_threshold = (SB_ERROR_THRESHOLD <<
>> >> SB_ERROR_THRESHOLD_SHIFT);
>> >> +       ret = regmap_write(llcc_bcast_regmap, DRP_ECC_ERROR_CFG,
>> >> +                          sb_err_threshold);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       /* Enable DRP in instance 2 of common interrupt enable
>> >> register */
>> >> +       ret = regmap_update_bits(llcc_bcast_regmap,
>> >> CMN_INTERRUPT_2_ENABLE,
>> >> +                                DRP0_INTERRUPT_ENABLE,
>> >> +                                DRP0_INTERRUPT_ENABLE);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       /* Enable ECC interrupts on Data Ram */
>> >> +       ret = regmap_write(llcc_bcast_regmap, DRP_INTERRUPT_ENABLE,
>> >> +                          SB_DB_DRP_INTERRUPT_ENABLE);
>> >> +       return ret;
>> >> +}
>> >> +
>> >> +/* Clear the error interrupt and counter registers */
>> >> +static int
>> >> +qcom_llcc_clear_errors_status(int err_type, struct llcc_drv_data
>> >> *drv)
>> >
>> > Another nit: errors_status is kind of weird. Maybe
>> > qcom_llcc_clear_errors or qcom_llcc_clear_error_status?
>> 
>> I'll update the name.
>> 
>> >
>> >> +{
>> >> +       int ret = 0;
>> >> +
>> >> +       switch (err_type) {
>> >> +       case LLCC_DRAM_CE:
>> >> +       case LLCC_DRAM_UE:
>> >> +               /* Clear the interrupt */
>> >> +               ret = regmap_write(drv->bcast_regmap,
>> >> DRP_INTERRUPT_CLEAR,
>> >> +                                  DRP_TRP_INT_CLEAR);
>> >> +               if (ret)
>> >> +                       return ret;
>> >> +
>> >> +               /* Clear the counters */
>> >> +               ret = regmap_write(drv->bcast_regmap,
>> >> DRP_ECC_ERROR_CNTR_CLEAR,
>> >> +                                  DRP_TRP_CNT_CLEAR);
>> >> +               if (ret)
>> >> +                       return ret;
>> >> +               break;
>> >> +       case LLCC_TRAM_CE:
>> >> +       case LLCC_TRAM_UE:
>> >> +               ret = regmap_write(drv->bcast_regmap,
>> >> TRP_INTERRUPT_0_CLEAR,
>> >> +                                  DRP_TRP_INT_CLEAR);
>> >> +               if (ret)
>> >> +                       return ret;
>> >> +
>> >> +               ret = regmap_write(drv->bcast_regmap,
>> >> TRP_ECC_ERROR_CNTR_CLEAR,
>> >> +                                  DRP_TRP_CNT_CLEAR);
>> >> +               if (ret)
>> >> +                       return ret;
>> >> +               break;
>> >
>> > A default case that errors or complains or both would be nice.
>> 
>> Ok, I had this thought too, but we never run into that scenario,
>> that's we don't ever call this function with any other types,
>> Had it been an API it makes sense to have a default case.
>> The internal functions require them too! I don't know!!
>> What do you think?
>> As we say, if it's good to have it, I'll add it.
> 
> I personally like the default case, I find it to be defensive against
> someone adding code later who passes the wrong value or type down.
> Others might disagree. It's up to you.

It makes sense to have a defensive code against someone adding the code 
later,
I'll add it.