Re: [PATCH v7] firmware: qcom: scm: introduce keep_mdt_buf flag in PAS context

[Sumit Garg]

Hi Mukesh,

On Sun, Sep 20, 2026 at 1:19 PM Mukesh Ojha
<mukesh.ojha@xxxxxxxxxxxxxxxx> wrote:
>
> The PAS image initialization path always retains the metadata buffer
> when a valid qcom_scm_pas_context is provided, even if the caller does
> not require it. This implicit behavior leads to unclear buffer ownership
> and forces new users of qcom_mdt_pas_load() to manually release
> metadata, which is error‑ prone and incorrect.
>
> Add a keep_mdt_buf flag to struct qcom_scm_pas_context to make metadata
> retention explicit.  Metadata buffers are now freed by default and are
> only preserved when this flag is set. qcom_q6v5_pas enables this during
> probe for contexts that require retained metadata for subsequent PAS
> operations, while existing callers continue to work unchanged.
>
> Signed-off-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>
> ---
> Changes in v7:
> - Since qcom_scm_pas_context is removed, v6 needs to be rebased removing
>   the changes related to it.
> - Link to v6: https://lore.kernel.org/lkml/20260805133759.2790755-1-mukesh.ojha@xxxxxxxxxxxxxxxx/
>

Please update the commit message to use qcom_pas_context instead.
Also, why don't we handle this case in the generic PAS wrapper since
it sounds like it would affect OP-TEE backend too?

-Sumit

> Changes in v6:
>    - Other patches from the series is merged.
>    - Removed dependency on below series by adding keep_mdt_buf
>      into qcom_scm_pas_context structure as well.
>      https://lore.kernel.org/lkml/20260702115835.167602-1-sumit.garg@xxxxxxxxxx/
>    - Addressed minor comment on the documentationi.
>     - Link to v5: 6/6 of https://lore.kernel.org/lkml/20260724182858.1868271-7-mukesh.ojha@xxxxxxxxxxxxxxxx/
>
>
>
>  drivers/firmware/qcom/qcom_scm.c       | 10 +++++++---
>  drivers/remoteproc/qcom_q6v5_pas.c     |  3 +++
>  include/linux/firmware/qcom/qcom_pas.h |  1 +
>  3 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 28411a76d1bf..81bb38401d54 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -625,7 +625,7 @@ static int qcom_scm_pas_prep_and_init_image(struct device *dev,
>         mdata_phys = qcom_tzmem_to_phys(mdata_buf);
>
>         ret = __qcom_scm_pas_init_image(dev, ctx->pas_id, mdata_phys, &res);
> -       if (ret < 0)
> +       if (ret < 0 || !ctx->keep_mdt_buf)
>                 qcom_tzmem_free(mdata_buf);
>         else
>                 ctx->ptr = mdata_buf;
> @@ -664,9 +664,13 @@ static int qcom_scm_pas_init_image(struct device *dev, u32 pas_id,
>         memcpy(mdata_buf, metadata, size);
>
>         ret = __qcom_scm_pas_init_image(dev, pas_id, mdata_phys, &res);
> -       if (ret < 0 || !ctx) {
> +
> +       /*
> +        * free the metadata on error or if client didn't request us to keep it.
> +        */
> +       if (ret < 0 || !ctx || !ctx->keep_mdt_buf) {
>                 dma_free_coherent(dev, size, mdata_buf, mdata_phys);
> -       } else if (ctx) {
> +       } else {
>                 ctx->ptr = mdata_buf;
>                 ctx->phys = mdata_phys;
>                 ctx->size = size;
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index 96a2436b777d..40cd0f101a67 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -733,6 +733,7 @@ static int qcom_pas_alloc_memory_region(struct qcom_pas *pas)
>         if (IS_ERR(pas->pas_ctx))
>                 return PTR_ERR(pas->pas_ctx);
>
> +       pas->pas_ctx->keep_mdt_buf = true;
>         if (!pas->dtb_pas_id)
>                 return 0;
>
> @@ -751,6 +752,8 @@ static int qcom_pas_alloc_memory_region(struct qcom_pas *pas)
>         if (IS_ERR(pas->dtb_pas_ctx))
>                 return PTR_ERR(pas->dtb_pas_ctx);
>
> +       pas->dtb_pas_ctx->keep_mdt_buf = true;
> +
>         return 0;
>  }
>
> diff --git a/include/linux/firmware/qcom/qcom_pas.h b/include/linux/firmware/qcom/qcom_pas.h
> index fb2ec3be6a16..1d132e89536e 100644
> --- a/include/linux/firmware/qcom/qcom_pas.h
> +++ b/include/linux/firmware/qcom/qcom_pas.h
> @@ -22,6 +22,7 @@ struct qcom_pas_context {
>         dma_addr_t phys;
>         ssize_t size;
>         bool use_tzmem;
> +       bool keep_mdt_buf;
>  };
>
>  static inline void __iomem *qcom_pas_ctx_map(struct qcom_pas_context *ctx)
> --
> 2.55.0
>