Re: [PATCH v4 5/6] soc: qcom: Add LLCC support for multi channel DDR

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On 6/28/2023 4:43 PM, Konrad Dybcio wrote:
On 28.06.2023 10:52, Komal Bajaj wrote:

On 6/23/2023 8:28 PM, Konrad Dybcio wrote:
On 23.06.2023 16:18, Komal Bajaj wrote:
Add LLCC support for multi channel DDR configuration
based on a feature register. Reading DDR channel
confiuration uses nvmem framework, so select the
dependency in Kconfig. Without this, there will be
errors while building the driver with COMPILE_TEST only.

Signed-off-by: Komal Bajaj <quic_kbajaj@xxxxxxxxxxx>
---
   drivers/soc/qcom/Kconfig     |  2 ++
   drivers/soc/qcom/llcc-qcom.c | 33 ++++++++++++++++++++++++++++++---
   2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index a491718f8064..cc9ad41c63aa 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -64,6 +64,8 @@ config QCOM_LLCC
       tristate "Qualcomm Technologies, Inc. LLCC driver"
       depends on ARCH_QCOM || COMPILE_TEST
       select REGMAP_MMIO
+    select NVMEM
+    select QCOM_SCM
       help
         Qualcomm Technologies, Inc. platform specific
         Last Level Cache Controller(LLCC) driver for platforms such as,
diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
index 6cf373da5df9..3c29612da1c5 100644
--- a/drivers/soc/qcom/llcc-qcom.c
+++ b/drivers/soc/qcom/llcc-qcom.c
@@ -12,6 +12,7 @@
   #include <linux/kernel.h>
   #include <linux/module.h>
   #include <linux/mutex.h>
+#include <linux/nvmem-consumer.h>
   #include <linux/of.h>
   #include <linux/of_device.h>
   #include <linux/regmap.h>
@@ -943,6 +944,19 @@ static int qcom_llcc_cfg_program(struct platform_device *pdev,
       return ret;
   }
   +static int qcom_llcc_get_cfg_index(struct platform_device *pdev, u8 *cfg_index)
+{
+    int ret;
+
+    ret = nvmem_cell_read_u8(&pdev->dev, "multi-chan-ddr", cfg_index);
+    if (ret == -ENOENT) {
+        *cfg_index = 0;
+        return 0;
+    }
+
+    return ret;
+}
+
   static int qcom_llcc_remove(struct platform_device *pdev)
   {
       /* Set the global pointer to a error code to avoid referencing it */
@@ -975,11 +989,13 @@ static int qcom_llcc_probe(struct platform_device *pdev)
       struct device *dev = &pdev->dev;
       int ret, i;
       struct platform_device *llcc_edac;
-    const struct qcom_llcc_config *cfg;
+    const struct qcom_llcc_config *cfg, *entry;
       const struct llcc_slice_config *llcc_cfg;
       u32 sz;
+    u8 cfg_index;
       u32 version;
       struct regmap *regmap;
+    u32 num_entries = 0;
         drv_data = devm_kzalloc(dev, sizeof(*drv_data), GFP_KERNEL);
       if (!drv_data) {
@@ -1040,8 +1056,19 @@ static int qcom_llcc_probe(struct platform_device *pdev)
         drv_data->version = version;
   -    llcc_cfg = cfg[0]->sct_data;
-    sz = cfg[0]->size;
+    ret = qcom_llcc_get_cfg_index(pdev, &cfg_index);
+    if (ret)
+        goto err;
+
+    for (entry = cfg; entry->sct_data; entry++, num_entries++)
+        ;
+    if (cfg_index >= num_entries || cfg_index < 0) {
cfg_index is an unsigned variable, it can never be < 0
Okay, will remove this condition.

+        ret = -EINVAL;
+        goto err;
+    }
+
if (cfg_index >= entry->size)? With that, you can also keep the config
entries non-0-terminated in the previous patch, saving a whole lot of RAM.
entry->size represents the size of sct table whereas num_entries represents the number
of sct tables that we can have. And by this check we are validating the value read from the
fuse register. Am I understanding your comment correctly?
Oh you're right.

I still see room for improvement, though.

For example, you duplicate assigning need_llcc_cfg, reg_offset
and edac_reg_offset. You can add a new struct, like "sct_config" and add
a pointer to sct_config[] & the length of this array to qcom_llcc_config.

Konrad

Okay, will follow this approach.


Konrad
+    llcc_cfg = cfg[cfg_index].sct_data;
+    sz = cfg[cfg_index].size;
         for (i = 0; i < sz; i++)
           if (llcc_cfg[i].slice_id > drv_data->max_slices)




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