Re: [PATCH v2] drm/amd/display: use proper context for logging

[Alex Deucher]

Bhawan, I assume you already committed this?

Thanks,

Alex

On Thu, Jul 23, 2026 at 1:10 PM Lakha, Bhawanpreet
<Bhawanpreet.Lakha@xxxxxxx> wrote:
>
> 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