Re: [PATCH v2 1/3] EDAC/loongson: Encode node and MC info into mc_idx

在 2026/8/5 21:43, Huacai Chen 写道:
> Hi, Qunqin,
>
> On Wed, Aug 5, 2026 at 5:09 PM Qunqin Zhao <[email protected]> wrote:
>> From: Wang Jinwei <[email protected]>
>>
>> On Loongson multi-node systems, memory controllers are distributed across
>> multiple nodes. Encode node and MC information into mc_idx so that sysfs
>> entries uniquely identify each controller.
>>
>> The driver gets mc-idx from ACPI _DSD property if firmware provides it.
>> If not, it falls back to edac_device_alloc_index() for legacy firmware
>> compatibility.
>>
>> The number of memory controllers per node (mcs-per-node) is obtained
>> from firmware via ACPI _DSD property, with a default of 4 for backward
>> compatibility. Validate that the firmware-provided value is non-zero to
>> prevent division by zero. The node and MC IDs are decoded from mc_idx:
>>      node = mc_idx / mcs_per_node
>>      mc = mc_idx % mcs_per_node
>>
>> Cc: Yulong Wang <[email protected]>
>> Cc: Dongyan Qian <[email protected]>
>> Cc: Chao Li <[email protected]>
>> Signed-off-by: Wang Jinwei <[email protected]>
>> Signed-off-by: Qunqin Zhao <[email protected]>
>> ---
>>   drivers/edac/loongson_edac.c | 35 ++++++++++++++++++++++++++++++-----
>>   1 file changed, 30 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/edac/loongson_edac.c b/drivers/edac/loongson_edac.c
>> index 38745800ed..abfc1e60e0 100644
>> --- a/drivers/edac/loongson_edac.c
>> +++ b/drivers/edac/loongson_edac.c
>> @@ -9,6 +9,7 @@
>>   #include <linux/io-64-nonatomic-lo-hi.h>
>>   #include <linux/module.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/property.h>
>>   #include "edac_module.h"
>>
>>   #define ECC_CS_COUNT_REG       0x18
>> @@ -23,6 +24,8 @@ struct loongson_edac_pvt {
>>           * register state.
>>           */
>>          int last_ce_count;
>> +       int mcs_per_node;
>> +       bool mc_idx_valid;
>>   };
>>
>>   static int read_ecc(struct mem_ctl_info *mci)
>> @@ -44,7 +47,8 @@ static int read_ecc(struct mem_ctl_info *mci)
>>   static void edac_check(struct mem_ctl_info *mci)
>>   {
>>          struct loongson_edac_pvt *pvt = mci->pvt_info;
>> -       int new, add;
>> +       char other_detail[64] = {0};
>> +       int new, add, node, mc;
>>
>>          new = read_ecc(mci);
>>          add = new - pvt->last_ce_count;
>> @@ -52,8 +56,14 @@ static void edac_check(struct mem_ctl_info *mci)
>>          if (add <= 0)
>>                  return;
>>
>> +       if (pvt->mc_idx_valid) {
>> +               node = mci->mc_idx / pvt->mcs_per_node;
>> +               mc = mci->mc_idx % pvt->mcs_per_node;
>> +               snprintf(other_detail, sizeof(other_detail), "node:%d mc:%d", node, mc);
>> +       }
>> +
>>          edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci, add,
>> -                            0, 0, 0, 0, 0, -1, "error", "");
>> +                            0, 0, 0, 0, 0, -1, "error", other_detail);
>>   }
>>
>>   static void dimm_config_init(struct mem_ctl_info *mci)
>> @@ -72,20 +82,26 @@ static void dimm_config_init(struct mem_ctl_info *mci)
>>          dimm->grain = 8;
>>   }
>>
>> -static void pvt_init(struct mem_ctl_info *mci, void __iomem *vbase)
>> +static void pvt_init(struct mem_ctl_info *mci, void __iomem *vbase,
>> +                    bool mc_idx_valid, int mcs_per_node)
>>   {
>>          struct loongson_edac_pvt *pvt = mci->pvt_info;
>>
>>          pvt->ecc_base = vbase;
>>          pvt->last_ce_count = read_ecc(mci);
>> +       pvt->mc_idx_valid = mc_idx_valid;
>> +       pvt->mcs_per_node = mcs_per_node;
>>   }
>>
>>   static int edac_probe(struct platform_device *pdev)
>>   {
>>          struct edac_mc_layer layers[2];
>>          struct mem_ctl_info *mci;
>> +       struct device *dev = &pdev->dev;
>>          void __iomem *vbase;
>> +       u32 mcs_per_node, mc_idx_u32;
> Why do we need mc_idx_u32? The code in V1 doesn't work?

V1 works. This is purely to fix the issue reported by sashiko:

"The mc_idx field is defined as an int in struct mem_ctl_info, but
device_property_read_u32() expects a u32 *. Should this be read into a
temporary u32 variable first?"

Should we ignore it?

>
>>          int ret;
>> +       bool mc_idx_valid = true;
>>
>>          vbase = devm_platform_ioremap_resource(pdev, 0);
>>          if (IS_ERR(vbase))
>> @@ -102,7 +118,6 @@ static int edac_probe(struct platform_device *pdev)
>>          if (mci == NULL)
>>                  return -ENOMEM;
>>
>> -       mci->mc_idx = edac_device_alloc_index();
>>          mci->mtype_cap = MEM_FLAG_RDDR4;
>>          mci->edac_ctl_cap = EDAC_FLAG_NONE;
>>          mci->edac_cap = EDAC_FLAG_NONE;
>> @@ -114,7 +129,17 @@ static int edac_probe(struct platform_device *pdev)
>>          mci->error_desc.grain = 8;
>>          mci->edac_check = edac_check;
>>
>> -       pvt_init(mci, vbase);
>> +       if (device_property_read_u32(dev, "mc-idx", &mc_idx_u32)) {
>> +               mci->mc_idx = edac_device_alloc_index();
>> +               mc_idx_valid = false;
>> +       } else {
>> +               mci->mc_idx = mc_idx_u32;
>> +       }
>> +
>> +       if (device_property_read_u32(dev, "mc-per-node", &mcs_per_node) || mcs_per_node == 0)
> The property should also be mcs-per-node.

OK

Thanks.

> Huacai
>
>> +               mcs_per_node = 4;
>> +
>> +       pvt_init(mci, vbase, mc_idx_valid, mcs_per_node);
>>          dimm_config_init(mci);
>>
>>          ret = edac_mc_add_mc(mci);
>> --
>> 2.47.3
>>
>>