[PATCH 0/2] mmc: mmci_sdmmc: fix dma api warnings

[PATCH 0/2] mmc: mmci_sdmmc: fix dma api warnings

[Ludovic Barre]

This patch series fixes warnings see with DMA_API_DEBUG_SG=y

Ludovic Barre (2):
  mmc: mmci_sdmmc: fix DMA API warning overlapping mappings
  mmc: mmci_sdmmc: fix DMA API warning max segment size

 drivers/mmc/host/mmci_stm32_sdmmc.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

-- 
2.17.1

[PATCH 1/2] mmc: mmci_sdmmc: fix DMA API warning overlapping mappings

[Ludovic Barre]

Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:
WARNING: CPU: 1 PID: 20 at kernel/dma/debug.c:500 add_dma_entry+0x16c/0x17c
DMA-API: exceeded 7 overlapping mappings of cacheline 0x031d2645
Modules linked in:
CPU: 1 PID: 20 Comm: kworker/1:1 Not tainted 5.5.0-rc2-00021-gdeda30999c2b-dirty #49
Hardware name: STM32 (Device Tree Support)
Workqueue: events_freezable mmc_rescan
[<c03138c0>] (unwind_backtrace) from [<c030d760>] (show_stack+0x10/0x14)
[<c030d760>] (show_stack) from [<c0f2eb28>] (dump_stack+0xc0/0xd4)
[<c0f2eb28>] (dump_stack) from [<c034a14c>] (__warn+0xd0/0xf8)
[<c034a14c>] (__warn) from [<c034a530>] (warn_slowpath_fmt+0x94/0xb8)
[<c034a530>] (warn_slowpath_fmt) from [<c03bca0c>] (add_dma_entry+0x16c/0x17c)
[<c03bca0c>] (add_dma_entry) from [<c03bdf54>] (debug_dma_map_sg+0xe4/0x3d4)
[<c03bdf54>] (debug_dma_map_sg) from [<c0d09244>] (sdmmc_idma_prep_data+0x94/0xf8)
[<c0d09244>] (sdmmc_idma_prep_data) from [<c0d05a2c>] (mmci_prep_data+0x2c/0xb0)
[<c0d05a2c>] (mmci_prep_data) from [<c0d073ec>] (mmci_start_data+0x134/0x2f0)
[<c0d073ec>] (mmci_start_data) from [<c0d078d0>] (mmci_request+0xe8/0x154)
[<c0d078d0>] (mmci_request) from [<c0cecb44>] (mmc_start_request+0x94/0xbc)

DMA api debug brings to light leaking dma-mappings, dma_map_sg and
dma_unmap_sg are not correctly balanced.

If a request is prepared, the dma_map/unmap are done in asynchronous
call pre_req (prep_data) and post_req (unprep_data). In this case
the dma-mapping is right balanced.

But if the request was not prepared, the data->host_cookie is
define to zero and the dma_map/unmap must be done in the request.
The dma_map is called by mmci_dma_start (prep_data), but there is
no dma_unmap in this case.

This patch adds dma_unmap_sg when the dma is finalized and
the data cookie is zero (request not prepared).

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
---
 drivers/mmc/host/mmci_stm32_sdmmc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index 14f99d8aa3f0..2965b1c062e1 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
@@ -188,6 +188,9 @@ static int sdmmc_idma_start(struct mmci_host *host, unsigned int *datactrl)
 static void sdmmc_idma_finalize(struct mmci_host *host, struct mmc_data *data)
 {
 	writel_relaxed(0, host->base + MMCI_STM32_IDMACTRLR);
+
+	if (!data->host_cookie)
+		sdmmc_idma_unprep_data(host, data, 0);
 }
 
 static void mmci_sdmmc_set_clkreg(struct mmci_host *host, unsigned int desired)
-- 
2.17.1

[PATCH 2/2] mmc: mmci_sdmmc: fix DMA API warning max segment size

[Ludovic Barre]

Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:
WARNING: CPU: 1 PID: 85 at kernel/dma/debug.c:1302 debug_dma_map_sg+0x2a0/0x3cc
mmci-pl18x 58005000.sdmmc: DMA-API: mapping sg segment longer than device claims to support [len=126976] [max=65536]

dma api debug checks and compares the segment size to
dma_get_max_seg_size (dev->dma_parms->max_segment_size),
the sdmmc variant has an internal DMA and should define
its max_segment_size constraint to avoid this warning.

This Patch defines the dev->dma_parms->max_segment_size
with the constraint already set for mmc core
(host->mmc->max_seg_size).

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
---
 drivers/mmc/host/mmci_stm32_sdmmc.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index 2965b1c062e1..51db30acf4dc 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
@@ -119,20 +119,19 @@ static void sdmmc_idma_unprep_data(struct mmci_host *host,
 static int sdmmc_idma_setup(struct mmci_host *host)
 {
 	struct sdmmc_idma *idma;
+	struct device *dev = mmc_dev(host->mmc);
 
-	idma = devm_kzalloc(mmc_dev(host->mmc), sizeof(*idma), GFP_KERNEL);
+	idma = devm_kzalloc(dev, sizeof(*idma), GFP_KERNEL);
 	if (!idma)
 		return -ENOMEM;
 
 	host->dma_priv = idma;
 
 	if (host->variant->dma_lli) {
-		idma->sg_cpu = dmam_alloc_coherent(mmc_dev(host->mmc),
-						   SDMMC_LLI_BUF_LEN,
+		idma->sg_cpu = dmam_alloc_coherent(dev, SDMMC_LLI_BUF_LEN,
 						   &idma->sg_dma, GFP_KERNEL);
 		if (!idma->sg_cpu) {
-			dev_err(mmc_dev(host->mmc),
-				"Failed to alloc IDMA descriptor\n");
+			dev_err(dev, "Failed to alloc IDMA descriptor\n");
 			return -ENOMEM;
 		}
 		host->mmc->max_segs = SDMMC_LLI_BUF_LEN /
@@ -143,7 +142,7 @@ static int sdmmc_idma_setup(struct mmci_host *host)
 		host->mmc->max_seg_size = host->mmc->max_req_size;
 	}
 
-	return 0;
+	return dma_set_max_seg_size(dev, host->mmc->max_seg_size);
 }
 
 static int sdmmc_idma_start(struct mmci_host *host, unsigned int *datactrl)
-- 
2.17.1

Re: [PATCH 1/2] mmc: mmci_sdmmc: fix DMA API warning overlapping mappings

[Ulf Hansson]

On Tue, 26 May 2020 at 17:51, Ludovic Barre <ludovic.barre@st.com> wrote:
>
> Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:
> WARNING: CPU: 1 PID: 20 at kernel/dma/debug.c:500 add_dma_entry+0x16c/0x17c
> DMA-API: exceeded 7 overlapping mappings of cacheline 0x031d2645
> Modules linked in:
> CPU: 1 PID: 20 Comm: kworker/1:1 Not tainted 5.5.0-rc2-00021-gdeda30999c2b-dirty #49
> Hardware name: STM32 (Device Tree Support)
> Workqueue: events_freezable mmc_rescan
> [<c03138c0>] (unwind_backtrace) from [<c030d760>] (show_stack+0x10/0x14)
> [<c030d760>] (show_stack) from [<c0f2eb28>] (dump_stack+0xc0/0xd4)
> [<c0f2eb28>] (dump_stack) from [<c034a14c>] (__warn+0xd0/0xf8)
> [<c034a14c>] (__warn) from [<c034a530>] (warn_slowpath_fmt+0x94/0xb8)
> [<c034a530>] (warn_slowpath_fmt) from [<c03bca0c>] (add_dma_entry+0x16c/0x17c)
> [<c03bca0c>] (add_dma_entry) from [<c03bdf54>] (debug_dma_map_sg+0xe4/0x3d4)
> [<c03bdf54>] (debug_dma_map_sg) from [<c0d09244>] (sdmmc_idma_prep_data+0x94/0xf8)
> [<c0d09244>] (sdmmc_idma_prep_data) from [<c0d05a2c>] (mmci_prep_data+0x2c/0xb0)
> [<c0d05a2c>] (mmci_prep_data) from [<c0d073ec>] (mmci_start_data+0x134/0x2f0)
> [<c0d073ec>] (mmci_start_data) from [<c0d078d0>] (mmci_request+0xe8/0x154)
> [<c0d078d0>] (mmci_request) from [<c0cecb44>] (mmc_start_request+0x94/0xbc)
>
> DMA api debug brings to light leaking dma-mappings, dma_map_sg and
> dma_unmap_sg are not correctly balanced.
>
> If a request is prepared, the dma_map/unmap are done in asynchronous
> call pre_req (prep_data) and post_req (unprep_data). In this case
> the dma-mapping is right balanced.
>
> But if the request was not prepared, the data->host_cookie is
> define to zero and the dma_map/unmap must be done in the request.
> The dma_map is called by mmci_dma_start (prep_data), but there is
> no dma_unmap in this case.
>
> This patch adds dma_unmap_sg when the dma is finalized and
> the data cookie is zero (request not prepared).
>
> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>

Applied for next by adding a fixes tag and a stable tag, thanks!

Fixes: 46b723dd867d ("mmc: mmci: add stm32 sdmmc variant")

Kind regards
Uffe


> ---
>  drivers/mmc/host/mmci_stm32_sdmmc.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> index 14f99d8aa3f0..2965b1c062e1 100644
> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> @@ -188,6 +188,9 @@ static int sdmmc_idma_start(struct mmci_host *host, unsigned int *datactrl)
>  static void sdmmc_idma_finalize(struct mmci_host *host, struct mmc_data *data)
>  {
>         writel_relaxed(0, host->base + MMCI_STM32_IDMACTRLR);
> +
> +       if (!data->host_cookie)
> +               sdmmc_idma_unprep_data(host, data, 0);
>  }
>
>  static void mmci_sdmmc_set_clkreg(struct mmci_host *host, unsigned int desired)
> --
> 2.17.1
>

Re: [PATCH 2/2] mmc: mmci_sdmmc: fix DMA API warning max segment size

[Ulf Hansson]

On Tue, 26 May 2020 at 17:51, Ludovic Barre <ludovic.barre@st.com> wrote:
>
> Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:
> WARNING: CPU: 1 PID: 85 at kernel/dma/debug.c:1302 debug_dma_map_sg+0x2a0/0x3cc
> mmci-pl18x 58005000.sdmmc: DMA-API: mapping sg segment longer than device claims to support [len=126976] [max=65536]
>
> dma api debug checks and compares the segment size to
> dma_get_max_seg_size (dev->dma_parms->max_segment_size),
> the sdmmc variant has an internal DMA and should define
> its max_segment_size constraint to avoid this warning.
>
> This Patch defines the dev->dma_parms->max_segment_size
> with the constraint already set for mmc core
> (host->mmc->max_seg_size).
>
> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>

Applied for next, thanks!

Note, a manual backport is needed for stable, as
dma_set_max_seg_size() will fail for older kernels.
We needed to revert 9495b7e92f7 ("driver core: platform: Initialize
dma_parms for platform devices"), for stable kernels [1].

Kind regards
Uffe

[1]
https://lkml.org/lkml/2020/5/26/1216


> ---
>  drivers/mmc/host/mmci_stm32_sdmmc.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> index 2965b1c062e1..51db30acf4dc 100644
> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> @@ -119,20 +119,19 @@ static void sdmmc_idma_unprep_data(struct mmci_host *host,
>  static int sdmmc_idma_setup(struct mmci_host *host)
>  {
>         struct sdmmc_idma *idma;
> +       struct device *dev = mmc_dev(host->mmc);
>
> -       idma = devm_kzalloc(mmc_dev(host->mmc), sizeof(*idma), GFP_KERNEL);
> +       idma = devm_kzalloc(dev, sizeof(*idma), GFP_KERNEL);
>         if (!idma)
>                 return -ENOMEM;
>
>         host->dma_priv = idma;
>
>         if (host->variant->dma_lli) {
> -               idma->sg_cpu = dmam_alloc_coherent(mmc_dev(host->mmc),
> -                                                  SDMMC_LLI_BUF_LEN,
> +               idma->sg_cpu = dmam_alloc_coherent(dev, SDMMC_LLI_BUF_LEN,
>                                                    &idma->sg_dma, GFP_KERNEL);
>                 if (!idma->sg_cpu) {
> -                       dev_err(mmc_dev(host->mmc),
> -                               "Failed to alloc IDMA descriptor\n");
> +                       dev_err(dev, "Failed to alloc IDMA descriptor\n");
>                         return -ENOMEM;
>                 }
>                 host->mmc->max_segs = SDMMC_LLI_BUF_LEN /
> @@ -143,7 +142,7 @@ static int sdmmc_idma_setup(struct mmci_host *host)
>                 host->mmc->max_seg_size = host->mmc->max_req_size;
>         }
>
> -       return 0;
> +       return dma_set_max_seg_size(dev, host->mmc->max_seg_size);
>  }
>
>  static int sdmmc_idma_start(struct mmci_host *host, unsigned int *datactrl)
> --
> 2.17.1
>