From 35ee1f499091c76bd5f5d52f5ef79c3568ac74a6 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 8 Apr 2022 12:30:29 -0700 Subject: [PATCH] cxl/mem: Replace redundant debug message with a comment cxl_mem_probe() already emits a log message when HDM operation can not be established. Delete the similar one in cxl_hdm_decode_init(). What is less obvious is why global_ctrl being enabled makes positive values of info->ranges irrelevant, and the Linux behavior with respect to the spec recommendation to mirror CXL Range registers with HDM Decoder Base + Size registers. Cc: Ben Widawsky Reviewed-by: Jonathan Cameron Reviewed-by: Davidlohr Bueso Link: https://lore.kernel.org/r/164944616743.454665.7055846627973202403.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams --- drivers/cxl/mem.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c index 3baae1332760..43e73d259207 100644 --- a/drivers/cxl/mem.c +++ b/drivers/cxl/mem.c @@ -107,11 +107,17 @@ __mock bool cxl_hdm_decode_init(struct cxl_dev_state *cxlds) global_ctrl = readl(crb + cmap->hdm_decoder.offset + CXL_HDM_DECODER_CTRL_OFFSET); global_enable = global_ctrl & CXL_HDM_DECODER_ENABLE; - if (!global_enable && info->ranges) { - dev_dbg(cxlds->dev, - "DVSEC ranges already programmed and HDM decoders not enabled.\n"); + + /* + * Per CXL 2.0 Section 8.1.3.8.3 and 8.1.3.8.4 DVSEC CXL Range 1 Base + * [High,Low] when HDM operation is enabled the range register values + * are ignored by the device, but the spec also recommends matching the + * DVSEC Range 1,2 to HDM Decoder Range 0,1. So, non-zero info->ranges + * are expected even though Linux does not require or maintain that + * match. + */ + if (!global_enable && info->ranges) goto out; - } retval = true;