Re: [PATCH v2] drm/amd/display: use proper context for logging
From: Lakha, Bhawanpreet
Date: Thu Jul 23 2026 - 13:28:43 EST
looks good, thank you
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@xxxxxxx>
Bhawan
________________________________________
From: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
Sent: July 23, 2026 12:25 AM
To: Deucher, Alexander <Alexander.Deucher@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@xxxxxxx>; Wentland, Harry <Harry.Wentland@xxxxxxx>; Li, Sun peng (Leo) <Sunpeng.Li@xxxxxxx>; Rodrigo Siqueira <siqueira@xxxxxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; David Airlie <airlied@xxxxxxxxx>; Simona Vetter <simona@xxxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx <amd-gfx@xxxxxxxxxxxxxxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH v2] drm/amd/display: use proper context for logging
The same as the rest of the code, get_ss_info_from_atombios() uses
calc_pll_cs->ctx->logger for logging. But calc_pll_cs->ctx is
initialized only later in calc_pll_max_vco_construct(). Therefore, any
output using DC_LOG_SYNC() leads to a NULL pointer deference in
get_ss_info_from_atombios().
According to Sashiko, the very same problem exists in
dce112_get_pix_clk_dividers() and dcn3_get_pix_clk_dividers() too.
To avoid accessing the NULL context, use clk_src->base.ctx->logger
everywhere. That context in base is initialized earlier in
dce110_clk_src_construct() and dce112_clk_src_construct(). Before
get_ss_info_from_atombios() or Sashiko's get_pix_clk_dividers functions
above are actually called. This is done by redefining DC_LOGGER to
CTX->logger.
Before:
dce110_clk_src_construct() did:
-> sets clk_src->base.ctx = ctx;
-> ss_info_from_atombios_create()
-> get_ss_info_from_atombios() <- uses calc_pll_cs->ctx # BOOM
-> calc_pll_max_vco_construct() <- sets calc_pll_cs->ctx
After:
dce110_clk_src_construct() does:
-> sets clk_src->base.ctx = ctx;
-> ss_info_from_atombios_create()
-> get_ss_info_from_atombios() <- uses clk_src->base.ctx
Closes: https://bugzilla.suse.com/show_bug.cgi?id=1271175
Closes: https://lore.kernel.org/all/a9ee54e6-2413-4156-9bde-d528ae3c63a3@xxxxxxxxxx/
Fixes: 1296423bf23c ("drm/amd/display: define DC_LOGGER for logger")
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
Cc: Lakha, Bhawanpreet <Bhawanpreet.Lakha@xxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Leo Li <sunpeng.li@xxxxxxx>
Cc: Rodrigo Siqueira <siqueira@xxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: "Christian König" <christian.koenig@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: Simona Vetter <simona@xxxxxxxx>
Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
---
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
[v2] Set DC_LOGGER to CTX->logger unconditionally (Bhawanpreet).
[v1] https://lore.kernel.org/all/20260722063210.1144266-1-jirislaby@xxxxxxxxxx/
---
.../drm/amd/display/dc/dce/dce_clock_source.c | 20 +++++++++----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
index ecb8493ec523..8e3862f6dac2 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
@@ -45,9 +45,7 @@
clk_src->base.ctx
#define DC_LOGGER \
- calc_pll_cs->ctx->logger
-#define DC_LOGGER_INIT() \
- struct calc_pll_clock_source *calc_pll_cs = &clk_src->calc_pll
+ CTX->logger
#undef FN
#define FN(reg_name, field_name) \
@@ -287,6 +285,7 @@ static bool calc_pll_dividers_in_range(
}
static uint32_t calculate_pixel_clock_pll_dividers(
+ struct dce110_clk_src *clk_src,
struct calc_pll_clock_source *calc_pll_cs,
struct pll_settings *pll_settings)
{
@@ -474,7 +473,7 @@ static uint32_t dce110_get_pix_clk_dividers_helper (
{
uint32_t field = 0;
uint32_t pll_calc_error = MAX_PLL_CALC_ERROR;
- DC_LOGGER_INIT();
+
/* Check if reference clock is external (not pcie/xtalin)
* HW Dce80 spec:
* 00 - PCIE_REFCLK, 01 - XTALIN, 02 - GENERICA, 03 - GENERICB
@@ -517,12 +516,14 @@ static uint32_t dce110_get_pix_clk_dividers_helper (
/*Calculate Dividers by HDMI object, no SS case or SS case */
pll_calc_error =
calculate_pixel_clock_pll_dividers(
+ clk_src,
&clk_src->calc_pll_hdmi,
pll_settings);
else
/*Calculate Dividers by default object, no SS case or SS case */
pll_calc_error =
calculate_pixel_clock_pll_dividers(
+ clk_src,
&clk_src->calc_pll,
pll_settings);
@@ -568,7 +569,6 @@ static uint32_t dce110_get_pix_clk_dividers(
{
struct dce110_clk_src *clk_src = TO_DCE110_CLK_SRC(cs);
uint32_t pll_calc_error = MAX_PLL_CALC_ERROR;
- DC_LOGGER_INIT();
if (pix_clk_params == NULL || pll_settings == NULL
|| pix_clk_params->requested_pix_clk_100hz == 0) {
@@ -600,7 +600,6 @@ static uint32_t dce112_get_pix_clk_dividers(
struct pll_settings *pll_settings)
{
struct dce110_clk_src *clk_src = TO_DCE110_CLK_SRC(cs);
- DC_LOGGER_INIT();
if (pix_clk_params == NULL || pll_settings == NULL
|| pix_clk_params->requested_pix_clk_100hz == 0) {
@@ -1442,8 +1441,6 @@ static uint32_t dcn3_get_pix_clk_dividers(
unsigned long long actual_pix_clk_100Hz = pix_clk_params ? pix_clk_params->requested_pix_clk_100hz : 0;
struct dce110_clk_src *clk_src = TO_DCE110_CLK_SRC(cs);
- DC_LOGGER_INIT();
-
if (pix_clk_params == NULL || pll_settings == NULL
|| pix_clk_params->requested_pix_clk_100hz == 0) {
DC_LOG_ERROR(
@@ -1513,7 +1510,6 @@ static const struct clock_source_funcs dce110_clk_src_funcs = {
.get_dp_dto_frequency_100hz = get_dp_dto_frequency_100hz
};
-
static void get_ss_info_from_atombios(
struct dce110_clk_src *clk_src,
enum as_signal_type as_signal,
@@ -1526,7 +1522,7 @@ static void get_ss_info_from_atombios(
struct spread_spectrum_info *ss_info_cur;
struct spread_spectrum_data *ss_data_cur;
uint32_t i;
- DC_LOGGER_INIT();
+
if (ss_entries_num == NULL) {
DC_LOG_SYNC(
"Invalid entry !!!\n");
@@ -1657,6 +1653,7 @@ static void ss_info_from_atombios_create(
}
static bool calc_pll_max_vco_construct(
+ struct dce110_clk_src *clk_src,
struct calc_pll_clock_source *calc_pll_cs,
struct calc_pll_clock_source_init_data *init_data)
{
@@ -1808,6 +1805,7 @@ bool dce110_clk_src_construct(
ss_info_from_atombios_create(clk_src);
if (!calc_pll_max_vco_construct(
+ clk_src,
&clk_src->calc_pll,
&calc_pll_cs_init_data)) {
ASSERT_CRITICAL(false);
@@ -1822,7 +1820,7 @@ bool dce110_clk_src_construct(
if (!calc_pll_max_vco_construct(
- &clk_src->calc_pll_hdmi, &calc_pll_cs_init_data_hdmi)) {
+ clk_src, &clk_src->calc_pll_hdmi, &calc_pll_cs_init_data_hdmi)) {
ASSERT_CRITICAL(false);
goto unexpected_failure;
}
--
2.55.0