diff options
| author | Albert Yang <yangzh0906@thundersoft.com> | 2026-01-23 12:53:38 +0300 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2026-02-23 14:06:55 +0300 |
| commit | ef7eb1a7094dbb5042ea1bed34193c1415fb9844 (patch) | |
| tree | ef009fd28581f63ea1032ad5ba968ea494eb1ef4 | |
| parent | d5159623162cc3d462ba1e661f8362c181756d65 (diff) | |
| download | linux-ef7eb1a7094dbb5042ea1bed34193c1415fb9844.tar.xz | |
mmc: sdhci: allow drivers to pre-allocate bounce buffer
Allow platform drivers to pre-allocate bounce buffer by checking if
host->bounce_buffer is already set before attempting allocation.
This enables platforms with specific DMA constraints (such as 32-bit
DMA on controllers that cannot access high memory) to use their own
reserved memory regions for the bounce buffer.
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Albert Yang <yangzh0906@thundersoft.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
| -rw-r--r-- | drivers/mmc/host/sdhci.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 1ff15fa9b042..b1a3cd574c84 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -4193,6 +4193,12 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host) unsigned int bounce_size; int ret; + /* Drivers may have already allocated the buffer */ + if (host->bounce_buffer) { + bounce_size = host->bounce_buffer_size; + max_blocks = bounce_size / 512; + goto out; + } /* * Cap the bounce buffer at 64KB. Using a bigger bounce buffer * has diminishing returns, this is probably because SD/MMC @@ -4241,6 +4247,7 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host) host->bounce_buffer_size = bounce_size; +out: /* Lie about this since we're bouncing */ mmc->max_segs = max_blocks; mmc->max_seg_size = bounce_size; |