2020-06-08 08:47:59

by Neil Armstrong

Subject: [PATCH] mmc: meson-gx: limit segments to 1 when dram-access-quirk is needed

The actual max_segs computation leads to failure while using the broadcom
sdio brcmfmac/bcmsdh driver, since the driver tries to make usage of scatter
gather.

But with the dram-access-quirk we use a 1,5K SRAM bounce buffer, and the
max_segs current value of 3 leads to max transfers to 4,5k, which doesn't work.

This patch sets max_segs to 1 to better describe the hardware limitation,
and fix the SDIO functionnality with the brcmfmac/bcmsdh driver on Amlogic
G12A/G12B SoCs on boards like SEI510 or Khadas VIM3.

Reported-by: Art Nikpal <[email protected]>
Reported-by: Christian Hewitt <[email protected]>
Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
Signed-off-by: Neil Armstrong <[email protected]>
---
drivers/mmc/host/meson-gx-mmc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 35400cf2a2e4..cfaf8e7e22ec 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -1143,9 +1143,11 @@ static int meson_mmc_probe(struct platform_device *pdev)

mmc->caps |= MMC_CAP_CMD23;
if (host->dram_access_quirk) {
+ /* Limit segments to 1 due to low available sram memory */
+ mmc->max_segs = 1;
/* Limit to the available sram memory */
- mmc->max_segs = SD_EMMC_SRAM_DATA_BUF_LEN / mmc->max_blk_size;
- mmc->max_blk_count = mmc->max_segs;
+ mmc->max_blk_count = SD_EMMC_SRAM_DATA_BUF_LEN /
+ mmc->max_blk_size;
} else {
mmc->max_blk_count = CMD_CFG_LENGTH_MASK;
mmc->max_segs = SD_EMMC_DESC_BUF_LEN /
--
2.22.0

2020-06-09 18:48:55

by Kevin Hilman

Subject: Re: [PATCH] mmc: meson-gx: limit segments to 1 when dram-access-quirk is needed

Neil Armstrong <[email protected]> writes:

> The actual max_segs computation leads to failure while using the broadcom
> sdio brcmfmac/bcmsdh driver, since the driver tries to make usage of scatter
> gather.
>
> But with the dram-access-quirk we use a 1,5K SRAM bounce buffer, and the
> max_segs current value of 3 leads to max transfers to 4,5k, which doesn't work.
>
> This patch sets max_segs to 1 to better describe the hardware limitation,
> and fix the SDIO functionnality with the brcmfmac/bcmsdh driver on Amlogic
> G12A/G12B SoCs on boards like SEI510 or Khadas VIM3.
>
> Reported-by: Art Nikpal <[email protected]>
> Reported-by: Christian Hewitt <[email protected]>
> Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
> Signed-off-by: Neil Armstrong <[email protected]>

Reviewed-by: Kevin Hilman <[email protected]>

2020-06-16 11:35:31

by Ulf Hansson

Subject: Re: [PATCH] mmc: meson-gx: limit segments to 1 when dram-access-quirk is needed

On Mon, 8 Jun 2020 at 10:45, Neil Armstrong <[email protected]> wrote:
>
> The actual max_segs computation leads to failure while using the broadcom
> sdio brcmfmac/bcmsdh driver, since the driver tries to make usage of scatter
> gather.
>
> But with the dram-access-quirk we use a 1,5K SRAM bounce buffer, and the
> max_segs current value of 3 leads to max transfers to 4,5k, which doesn't work.
>
> This patch sets max_segs to 1 to better describe the hardware limitation,
> and fix the SDIO functionnality with the brcmfmac/bcmsdh driver on Amlogic
> G12A/G12B SoCs on boards like SEI510 or Khadas VIM3.
>
> Reported-by: Art Nikpal <[email protected]>
> Reported-by: Christian Hewitt <[email protected]>
> Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
> Signed-off-by: Neil Armstrong <[email protected]>

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

Kind regards
Uffe


> ---
> drivers/mmc/host/meson-gx-mmc.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 35400cf2a2e4..cfaf8e7e22ec 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -1143,9 +1143,11 @@ static int meson_mmc_probe(struct platform_device *pdev)
>
> mmc->caps |= MMC_CAP_CMD23;
> if (host->dram_access_quirk) {
> + /* Limit segments to 1 due to low available sram memory */
> + mmc->max_segs = 1;
> /* Limit to the available sram memory */
> - mmc->max_segs = SD_EMMC_SRAM_DATA_BUF_LEN / mmc->max_blk_size;
> - mmc->max_blk_count = mmc->max_segs;
> + mmc->max_blk_count = SD_EMMC_SRAM_DATA_BUF_LEN /
> + mmc->max_blk_size;
> } else {
> mmc->max_blk_count = CMD_CFG_LENGTH_MASK;
> mmc->max_segs = SD_EMMC_DESC_BUF_LEN /
> --
> 2.22.0
>