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Message-ID: <iweswdjn6owhotezqdrdk5q7c4npazw5mb4zgurpfc3kb4d27b@fdywmzmvbn6d>
Date: Thu, 11 Dec 2025 15:38:02 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Kumari Pallavi <kumari.pallavi@....qualcomm.com>
Cc: kpallavi@....qualcomm.com, srini@...nel.org, amahesh@....qualcomm.com,
arnd@...db.de, gregkh@...uxfoundation.org, robh@...nel.org,
krzk+dt@...nel.org, conor+dt@...nel.org, quic_bkumar@...cinc.com,
ekansh.gupta@....qualcomm.com, linux-kernel@...r.kernel.org,
quic_chennak@...cinc.com, dri-devel@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
jingyi.wang@....qualcomm.com, aiqun.yu@....qualcomm.com,
ktadakam@....qualcomm.com
Subject: Re: [PATCH v6 3/4] misc: fastrpc: Add support for new DSP IOVA
formatting
On Thu, Dec 11, 2025 at 03:39:32PM +0530, Kumari Pallavi wrote:
> Implement the new IOVA formatting required by the DSP architecture change
> on Kaanapali SoC. Place the SID for DSP DMA transactions at bit 56 in the
> physical address. This placement is necessary for the DSPs to correctly
> identify streams and operate as intended.
> To address this, set SID position to bit 56 via OF matching on the fastrpc
> node; otherwise, default to legacy 32-bit placement.
> This change ensures consistent SID placement across DSPs.
>
> Signed-off-by: Kumari Pallavi <kumari.pallavi@....qualcomm.com>
> ---
> drivers/misc/fastrpc.c | 61 ++++++++++++++++++++++++++++++++++++------
> 1 file changed, 53 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index eb9501fe79bc..af92876f1cc1 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -22,6 +22,7 @@
> #include <linux/firmware/qcom/qcom_scm.h>
> #include <uapi/misc/fastrpc.h>
> #include <linux/of_reserved_mem.h>
> +#include <linux/bits.h>
>
> #define ADSP_DOMAIN_ID (0)
> #define MDSP_DOMAIN_ID (1)
> @@ -33,7 +34,6 @@
> #define FASTRPC_ALIGN 128
> #define FASTRPC_MAX_FDLIST 16
> #define FASTRPC_MAX_CRCLIST 64
> -#define FASTRPC_PHYS(p) ((p) & 0xffffffff)
> #define FASTRPC_CTX_MAX (256)
> #define FASTRPC_INIT_HANDLE 1
> #define FASTRPC_DSP_UTILITIES_HANDLE 2
> @@ -105,6 +105,23 @@
>
> #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
>
> +/* Extract SMMU PA from consolidated IOVA */
> +static inline dma_addr_t fastrpc_ipa_to_dma_addr(dma_addr_t iova, u32 sid_pos)
> +{
> + if (!sid_pos)
> + return 0;
> + return iova & GENMASK_ULL(sid_pos - 1, 0);
> +}
> +
> +/*
> + * Prepare the consolidated iova to send to DSP by prepending the SID
> + * to smmu PA at the appropriate position
> + */
> +static inline u64 fastrpc_compute_sid_offset(u64 sid, u32 sid_pos)
> +{
> + return sid << sid_pos;
> +}
> +
> struct fastrpc_phy_page {
> dma_addr_t addr; /* dma address */
> u64 size; /* size of contiguous region */
> @@ -257,6 +274,10 @@ struct fastrpc_session_ctx {
> bool valid;
> };
>
> +struct fastrpc_soc_data {
> + u32 sid_pos;
> +};
> +
> struct fastrpc_channel_ctx {
> int domain_id;
> int sesscount;
> @@ -278,6 +299,7 @@ struct fastrpc_channel_ctx {
> bool secure;
> bool unsigned_support;
> u64 dma_mask;
> + const struct fastrpc_soc_data *soc_data;
> };
>
> struct fastrpc_device {
> @@ -390,7 +412,8 @@ static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd,
> static void fastrpc_buf_free(struct fastrpc_buf *buf)
> {
> dma_free_coherent(buf->dev, buf->size, buf->virt,
> - FASTRPC_PHYS(buf->dma_addr));
> + fastrpc_ipa_to_dma_addr(buf->dma_addr,
> + buf->fl->cctx->soc_data->sid_pos));
fastrpc_ipa_to_dma_addr(fl->ccxtx, buf->dma_addr)
> kfree(buf);
> }
>
> @@ -440,7 +463,8 @@ static int fastrpc_buf_alloc(struct fastrpc_user *fl, struct device *dev,
> buf = *obuf;
>
> if (fl->sctx && fl->sctx->sid)
> - buf->dma_addr += ((u64)fl->sctx->sid << 32);
> + buf->dma_addr += fastrpc_compute_sid_offset(fl->sctx->sid,
> + fl->cctx->soc_data->sid_pos);
fastrpc_sid_offset(fl->cctx, fl->sctx)
>
> return 0;
> }
> @@ -685,7 +709,9 @@ static int fastrpc_dma_buf_attach(struct dma_buf *dmabuf,
> return -ENOMEM;
>
> ret = dma_get_sgtable(buffer->dev, &a->sgt, buffer->virt,
> - FASTRPC_PHYS(buffer->dma_addr), buffer->size);
> + fastrpc_ipa_to_dma_addr(buffer->dma_addr,
> + buffer->fl->cctx->soc_data->sid_pos),
> + buffer->size);
> if (ret < 0) {
> dev_err(buffer->dev, "failed to get scatterlist from DMA API\n");
> kfree(a);
> @@ -734,7 +760,8 @@ static int fastrpc_mmap(struct dma_buf *dmabuf,
> dma_resv_assert_held(dmabuf->resv);
>
> return dma_mmap_coherent(buf->dev, vma, buf->virt,
> - FASTRPC_PHYS(buf->dma_addr), size);
> + fastrpc_ipa_to_dma_addr(buf->dma_addr,
> + buf->fl->cctx->soc_data->sid_pos), size);
> }
>
> static const struct dma_buf_ops fastrpc_dma_buf_ops = {
> @@ -747,6 +774,12 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = {
> .release = fastrpc_release,
> };
>
> +static dma_addr_t fastrpc_compute_dma_addr(struct fastrpc_user *fl, dma_addr_t sg_dma_addr)
> +{
> + return sg_dma_addr + fastrpc_compute_sid_offset(fl->sctx->sid,
> + fl->cctx->soc_data->sid_pos);
> +}
> +
> static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
> u64 len, u32 attr, struct fastrpc_map **ppmap)
> {
> @@ -788,8 +821,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
> if (attr & FASTRPC_ATTR_SECUREMAP) {
> map->dma_addr = sg_phys(map->table->sgl);
> } else {
> - map->dma_addr = sg_dma_address(map->table->sgl);
> - map->dma_addr += ((u64)fl->sctx->sid << 32);
> + map->dma_addr = fastrpc_compute_dma_addr(fl, sg_dma_address(map->table->sgl));
> }
Now you can drop curve brackets around.
> for_each_sg(map->table->sgl, sgl, map->table->nents,
> sgl_index)
--
With best wishes
Dmitry
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