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mmc: dw_mmc: Add desc_num field for clarity

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The ring_size field in struct dw_mci is misleadingly named.
Despite its name, it does not represent the size of the descriptor
ring buffer in bytes, but rather the number of descriptors allocated
within the fixed-size ring buffer.

The actual ring buffer size is fixed at PAGE_SIZE (or DESC_RING_BUF_SZ,
which equals PAGE_SIZE). Within this buffer, we allocate either
struct idmac_desc or struct idmac_desc_64addr descriptors, and
ring_size stores the count of these descriptors.

This naming has caused confusion, as it's also used to set
mmc->max_segs (the maximum number of scatter-gather segments),
which logically corresponds to the number of descriptors, not a
size in bytes.

No functional change is introduced by this naming-only patch.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Ulf Hansson <ulfh@kernel.org>
This commit is contained in:
Shawn Lin 2026-05-29 09:17:39 +08:00 committed by Ulf Hansson
parent 94044acc20
commit b99062da21
2 changed files with 10 additions and 10 deletions
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16
drivers/mmc/host/dw_mmc.c
View File

@ -490,12 +490,12 @@ static int dw_mci_idmac_init(struct dw_mci *host)
if (host->dma_64bit_address == 1) {
struct idmac_desc_64addr *p;
/* Number of descriptors in the ring buffer */
host->ring_size =
host->desc_num =
DESC_RING_BUF_SZ / sizeof(struct idmac_desc_64addr);
/* Forward link the descriptor list */
for (i = 0, p = host->sg_cpu; i < host->ring_size - 1;
for (i = 0, p = host->sg_cpu; i < host->desc_num - 1;
i++, p++) {
p->des6 = (host->sg_dma +
(sizeof(struct idmac_desc_64addr) *
@ -518,13 +518,13 @@ static int dw_mci_idmac_init(struct dw_mci *host)
} else {
struct idmac_desc *p;
/* Number of descriptors in the ring buffer */
host->ring_size =
host->desc_num =
DESC_RING_BUF_SZ / sizeof(struct idmac_desc);
/* Forward link the descriptor list */
for (i = 0, p = host->sg_cpu;
i < host->ring_size - 1;
i < host->desc_num - 1;
i++, p++) {
p->des3 = cpu_to_le32(host->sg_dma +
(sizeof(struct idmac_desc) * (i + 1)));
@ -2857,10 +2857,10 @@ static int dw_mci_init_host(struct dw_mci *host)
/* Useful defaults if platform data is unset. */
if (host->use_dma == TRANS_MODE_IDMAC) {
mmc->max_segs = host->ring_size;
mmc->max_segs = host->desc_num;
mmc->max_blk_size = 65535;
mmc->max_seg_size = 0x1000;
mmc->max_req_size = mmc->max_seg_size * host->ring_size;
mmc->max_req_size = mmc->max_seg_size * host->desc_num;
mmc->max_blk_count = mmc->max_req_size / 512;
} else if (host->use_dma == TRANS_MODE_EDMAC) {
mmc->max_segs = 64;

4
drivers/mmc/host/dw_mmc.h
View File

@ -79,7 +79,7 @@ struct dw_mci_dma_slave {
* @dma_ops: Pointer to DMA callbacks.
* @cmd_status: Snapshot of SR taken upon completion of the current
* command. Only valid when EVENT_CMD_COMPLETE is pending.
* @ring_size: Buffer size for idma descriptors.
* @desc_num: Number of idmac descriptors available.
* @dms: structure of slave-dma private data.
* @phy_regs: physical address of controller's register map
* @data_status: Snapshot of SR taken upon completion of the current
@ -186,7 +186,7 @@ struct dw_mci {
void *sg_cpu;
const struct dw_mci_dma_ops *dma_ops;
/* For idmac */
unsigned int ring_size;
unsigned short desc_num;
/* For edmac */
struct dw_mci_dma_slave *dms;