[PATCH 1/2] soc: qcom: llcc: Add per-slice counter and common llcc slice descriptor
From: Francisco Munoz Ruiz
Date: Thu Mar 05 2026 - 22:15:45 EST
From: Unnathi Chalicheemala <unnathi.chalicheemala@xxxxxxxxxxxxxxxx>
Fix incorrect slice activation/deactivation accounting by replacing the
bitmap-based activation tracking with per-slice atomic reference counters.
This resolves mismatches that occur when multiple client drivers vote for
the same slice or when llcc_slice_getd() is called multiple times.
As part of this fix, simplify slice descriptor handling by eliminating
dynamic allocation. llcc_slice_getd() now returns a pointer to a
preallocated descriptor, removing the need for repeated allocation/free
cycles and ensuring consistent reference tracking across all users.
Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@xxxxxxxxxxxxxxxx>
Signed-off-by: Francisco Munoz Ruiz <francisco.ruiz@xxxxxxxxxxxxxxxx>
Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
---
drivers/soc/qcom/llcc-qcom.c | 57 +++++++++++++++++++-------------------
include/linux/soc/qcom/llcc-qcom.h | 8 +++---
2 files changed, 32 insertions(+), 33 deletions(-)
diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
index ad5899d083f3..2e7f05df93a6 100644
--- a/drivers/soc/qcom/llcc-qcom.c
+++ b/drivers/soc/qcom/llcc-qcom.c
@@ -5,7 +5,6 @@
*/
#include <linux/bitfield.h>
-#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/device.h>
@@ -4431,8 +4430,7 @@ static struct llcc_drv_data *drv_data = (void *) -EPROBE_DEFER;
struct llcc_slice_desc *llcc_slice_getd(u32 uid)
{
const struct llcc_slice_config *cfg;
- struct llcc_slice_desc *desc;
- u32 sz, count;
+ u32 sz, i;
if (IS_ERR(drv_data))
return ERR_CAST(drv_data);
@@ -4440,21 +4438,14 @@ struct llcc_slice_desc *llcc_slice_getd(u32 uid)
cfg = drv_data->cfg;
sz = drv_data->cfg_size;
- for (count = 0; cfg && count < sz; count++, cfg++)
+ for (i = 0; cfg && i < sz; i++, cfg++)
if (cfg->usecase_id == uid)
break;
- if (count == sz || !cfg)
+ if (i == sz)
return ERR_PTR(-ENODEV);
- desc = kzalloc_obj(*desc);
- if (!desc)
- return ERR_PTR(-ENOMEM);
-
- desc->slice_id = cfg->slice_id;
- desc->slice_size = cfg->max_cap;
-
- return desc;
+ return &drv_data->desc[i];
}
EXPORT_SYMBOL_GPL(llcc_slice_getd);
@@ -4465,7 +4456,7 @@ EXPORT_SYMBOL_GPL(llcc_slice_getd);
void llcc_slice_putd(struct llcc_slice_desc *desc)
{
if (!IS_ERR_OR_NULL(desc))
- kfree(desc);
+ return;
}
EXPORT_SYMBOL_GPL(llcc_slice_putd);
@@ -4541,7 +4532,8 @@ int llcc_slice_activate(struct llcc_slice_desc *desc)
return -EINVAL;
mutex_lock(&drv_data->lock);
- if (test_bit(desc->slice_id, drv_data->bitmap)) {
+ /* Already active; try to take another reference. */
+ if (refcount_inc_not_zero(&desc->refcount)) {
mutex_unlock(&drv_data->lock);
return 0;
}
@@ -4555,7 +4547,8 @@ int llcc_slice_activate(struct llcc_slice_desc *desc)
return ret;
}
- __set_bit(desc->slice_id, drv_data->bitmap);
+ /* Set first reference */
+ refcount_set(&desc->refcount, 1);
mutex_unlock(&drv_data->lock);
return ret;
@@ -4581,10 +4574,12 @@ int llcc_slice_deactivate(struct llcc_slice_desc *desc)
return -EINVAL;
mutex_lock(&drv_data->lock);
- if (!test_bit(desc->slice_id, drv_data->bitmap)) {
+ /* refcount > 1, drop one ref and we’re done. */
+ if (refcount_dec_not_one(&desc->refcount)) {
mutex_unlock(&drv_data->lock);
return 0;
}
+
act_ctrl_val = ACT_CTRL_OPCODE_DEACTIVATE << ACT_CTRL_OPCODE_SHIFT;
ret = llcc_update_act_ctrl(desc->slice_id, act_ctrl_val,
@@ -4594,7 +4589,8 @@ int llcc_slice_deactivate(struct llcc_slice_desc *desc)
return ret;
}
- __clear_bit(desc->slice_id, drv_data->bitmap);
+ /* Finalize: atomically transition 1 -> 0 */
+ WARN_ON_ONCE(!refcount_dec_if_one(&desc->refcount));
mutex_unlock(&drv_data->lock);
return ret;
@@ -4638,7 +4634,7 @@ static int _qcom_llcc_cfg_program(const struct llcc_slice_config *config,
u32 attr1_val;
u32 attr0_val;
u32 max_cap_cacheline;
- struct llcc_slice_desc desc;
+ struct llcc_slice_desc *desc;
attr1_val = config->cache_mode;
attr1_val |= config->probe_target_ways << ATTR1_PROBE_TARGET_WAYS_SHIFT;
@@ -4787,8 +4783,11 @@ static int _qcom_llcc_cfg_program(const struct llcc_slice_config *config,
}
if (config->activate_on_init) {
- desc.slice_id = config->slice_id;
- ret = llcc_slice_activate(&desc);
+ desc = llcc_slice_getd(config->usecase_id);
+ if (IS_ERR(desc))
+ return PTR_ERR(desc);
+
+ ret = llcc_slice_activate(desc);
}
return ret;
@@ -5101,18 +5100,18 @@ static int qcom_llcc_probe(struct platform_device *pdev)
llcc_cfg = cfg->sct_data;
sz = cfg->size;
-
- for (i = 0; i < sz; i++)
- if (llcc_cfg[i].slice_id > drv_data->max_slices)
- drv_data->max_slices = llcc_cfg[i].slice_id;
-
- drv_data->bitmap = devm_bitmap_zalloc(dev, drv_data->max_slices,
- GFP_KERNEL);
- if (!drv_data->bitmap) {
+ drv_data->desc = devm_kcalloc(dev, sz, sizeof(struct llcc_slice_desc), GFP_KERNEL);
+ if (!drv_data->desc) {
ret = -ENOMEM;
goto err;
}
+ for (i = 0; i < sz; i++) {
+ drv_data->desc[i].slice_id = llcc_cfg[i].slice_id;
+ drv_data->desc[i].slice_size = llcc_cfg[i].max_cap;
+ refcount_set(&drv_data->desc[i].refcount, 0);
+ }
+
drv_data->cfg = llcc_cfg;
drv_data->cfg_size = sz;
drv_data->edac_reg_offset = cfg->edac_reg_offset;
diff --git a/include/linux/soc/qcom/llcc-qcom.h b/include/linux/soc/qcom/llcc-qcom.h
index 8243ab3a12a8..227125d84318 100644
--- a/include/linux/soc/qcom/llcc-qcom.h
+++ b/include/linux/soc/qcom/llcc-qcom.h
@@ -91,10 +91,12 @@
* struct llcc_slice_desc - Cache slice descriptor
* @slice_id: llcc slice id
* @slice_size: Size allocated for the llcc slice
+ * @refcount: Atomic counter to track activate/deactivate calls
*/
struct llcc_slice_desc {
u32 slice_id;
size_t slice_size;
+ refcount_t refcount;
};
/**
@@ -152,11 +154,10 @@ struct llcc_edac_reg_offset {
* @edac_reg_offset: Offset of the LLCC EDAC registers
* @lock: mutex associated with each slice
* @cfg_size: size of the config data table
- * @max_slices: max slices as read from device tree
* @num_banks: Number of llcc banks
- * @bitmap: Bit map to track the active slice ids
* @ecc_irq: interrupt for llcc cache error detection and reporting
* @ecc_irq_configured: 'True' if firmware has already configured the irq propagation
+ * @desc: Array pointer of pre-allocated LLCC slice descriptors
* @version: Indicates the LLCC version
*/
struct llcc_drv_data {
@@ -167,12 +168,11 @@ struct llcc_drv_data {
const struct llcc_edac_reg_offset *edac_reg_offset;
struct mutex lock;
u32 cfg_size;
- u32 max_slices;
u32 num_banks;
- unsigned long *bitmap;
int ecc_irq;
bool ecc_irq_configured;
u32 version;
+ struct llcc_slice_desc *desc;
};
#if IS_ENABLED(CONFIG_QCOM_LLCC)
--
2.34.1