>-----Original Message-----
>From: fan <nifan.cxl@xxxxxxxxx>
>Sent: 25 April 2024 00:19
>To: Shiju Jose <shiju.jose@xxxxxxxxxx>
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>Linuxarm <linuxarm@xxxxxxxxxx>
>Subject: Re: [RFC PATCH v8 03/10] cxl/mbox: Add GET_FEATURE mailbox
>command
>
>On Sat, Apr 20, 2024 at 12:47:12AM +0800, shiju.jose@xxxxxxxxxx wrote:
>> From: Shiju Jose <shiju.jose@xxxxxxxxxx>
>>
>> Add support for GET_FEATURE mailbox command.
>>
>> CXL spec 3.1 section 8.2.9.6 describes optional device specific features.
>> The settings of a feature can be retrieved using Get Feature command.
>>
>> Signed-off-by: Shiju Jose <shiju.jose@xxxxxxxxxx>
>> ---
>> drivers/cxl/core/mbox.c | 53
>+++++++++++++++++++++++++++++++++++++++++
>> drivers/cxl/cxlmem.h | 28 ++++++++++++++++++++++
>> 2 files changed, 81 insertions(+)
>>
>> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index
>> 82e279b821e2..999965871048 100644
>> --- a/drivers/cxl/core/mbox.c
>> +++ b/drivers/cxl/core/mbox.c
>> @@ -1318,6 +1318,59 @@ int cxl_get_supported_features(struct
>> cxl_memdev_state *mds, }
>> EXPORT_SYMBOL_NS_GPL(cxl_get_supported_features, CXL);
>>
>> +size_t cxl_get_feature(struct cxl_memdev_state *mds,
>> + const uuid_t feat_uuid, void *feat_out,
>> + size_t feat_out_size,
>> + size_t feat_out_min_size,
>> + enum cxl_get_feat_selection selection) {
>> + struct cxl_dev_state *cxlds = &mds->cxlds;
>> + struct cxl_mbox_get_feat_in pi;
>> + struct cxl_mbox_cmd mbox_cmd;
>> + size_t data_rcvd_size = 0;
>> + size_t data_to_rd_size, size_out;
>> + int rc;
>> +
>> + if (feat_out_size < feat_out_min_size) {
>> + dev_err(cxlds->dev,
>> + "%s: feature out buffer size(%lu) is not big enough\n",
>> + __func__, feat_out_size);
>> + return 0;
>> + }
>> +
>> + if (feat_out_size <= mds->payload_size)
>> + size_out = feat_out_size;
>> + else
>> + size_out = mds->payload_size;
>
>Using min() instead?
> size_out = min(feat_out_size, mds->payload_size)
Will do.
>
>> + pi.uuid = feat_uuid;
>> + pi.selection = selection;
>> + do {
>> + if ((feat_out_min_size - data_rcvd_size) <= mds->payload_size)
>> + data_to_rd_size = feat_out_min_size - data_rcvd_size;
>> + else
>> + data_to_rd_size = mds->payload_size;
>
>data_to_rd_size = min(feat_out_min_size - data_rcvd_size, mds->payload_size);
Will do.
>
>It seems feat_out_min_size is always the same as feat_out_size in this series,
>what is it for? For the loop here, my understanding is we need to fill up the out
>buffer multiple times if the feature cannot be held in a call, so it seems
>feat_out_min_size should be feat_out_size here.
feat_out_size and feat_out_min_size added separately because this function is a common interface
and it might be useful for the features like DDR5 ECS Control, where the Get feature output payload
size is relatively high and actually required data is small, contains DDR5 ECS control feature readable attributes for N number of memory media FRUs.
>
>Fan
>
>> +
>> + pi.offset = cpu_to_le16(data_rcvd_size);
>> + pi.count = cpu_to_le16(data_to_rd_size);
>> +
>> + mbox_cmd = (struct cxl_mbox_cmd) {
>> + .opcode = CXL_MBOX_OP_GET_FEATURE,
>> + .size_in = sizeof(pi),
>> + .payload_in = &pi,
>> + .size_out = size_out,
>> + .payload_out = feat_out + data_rcvd_size,
>> + .min_out = data_to_rd_size,
>> + };
>> + rc = cxl_internal_send_cmd(mds, &mbox_cmd);
>> + if (rc < 0 || mbox_cmd.size_out == 0)
>> + return 0;
>> + data_rcvd_size += mbox_cmd.size_out;
>> + } while (data_rcvd_size < feat_out_min_size);
>> +
>> + return data_rcvd_size;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_get_feature, CXL);
>> +
>> int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
>> struct cxl_region *cxlr)
>> {
>> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index
>> 06231e63373e..c822eb30e6d1 100644
>> --- a/drivers/cxl/cxlmem.h
>> +++ b/drivers/cxl/cxlmem.h
>> @@ -528,6 +528,7 @@ enum cxl_opcode {
>> CXL_MBOX_OP_GET_SUPPORTED_LOGS = 0x0400,
>> CXL_MBOX_OP_GET_LOG = 0x0401,
>> CXL_MBOX_OP_GET_SUPPORTED_FEATURES = 0x0500,
>> + CXL_MBOX_OP_GET_FEATURE = 0x0501,
>> CXL_MBOX_OP_IDENTIFY = 0x4000,
>> CXL_MBOX_OP_GET_PARTITION_INFO = 0x4100,
>> CXL_MBOX_OP_SET_PARTITION_INFO = 0x4101,
>> @@ -754,6 +755,28 @@ struct cxl_mbox_get_supp_feats_out {
>> struct cxl_mbox_supp_feat_entry feat_entries[]; } __packed;
>>
>> +/*
>> + * Get Feature CXL 3.1 Spec 8.2.9.6.2 */
>> +
>> +/*
>> + * Get Feature input payload
>> + * CXL rev 3.1 section 8.2.9.6.2 Table 8-99 */ enum
>> +cxl_get_feat_selection {
>> + CXL_GET_FEAT_SEL_CURRENT_VALUE,
>> + CXL_GET_FEAT_SEL_DEFAULT_VALUE,
>> + CXL_GET_FEAT_SEL_SAVED_VALUE,
>> + CXL_GET_FEAT_SEL_MAX
>> +};
>> +
>> +struct cxl_mbox_get_feat_in {
>> + uuid_t uuid;
>> + __le16 offset;
>> + __le16 count;
>> + u8 selection;
>> +} __packed;
>> +
>> /* Get Poison List CXL 3.0 Spec 8.2.9.8.4.1 */ struct
>> cxl_mbox_poison_in {
>> __le64 offset;
>> @@ -888,6 +911,11 @@ int cxl_set_timestamp(struct cxl_memdev_state
>> *mds); int cxl_get_supported_features(struct cxl_memdev_state *mds,
>> u32 count, u16 start_index,
>> struct cxl_mbox_get_supp_feats_out *feats_out);
>> +size_t cxl_get_feature(struct cxl_memdev_state *mds,
>> + const uuid_t feat_uuid, void *feat_out,
>> + size_t feat_out_size,
>> + size_t feat_out_min_size,
>> + enum cxl_get_feat_selection selection);
>> int cxl_poison_state_init(struct cxl_memdev_state *mds); int
>> cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
>> struct cxl_region *cxlr);
>> --
>> 2.34.1
>>
Thanks,
Shiju
