2010-02-11 14:20:31

by kishore kadiyala

[permalink] [raw]

Subject: [PATCH] OMAP: Fix for bus width which improves SD card's peformance.

---

This patch improves low speeds for SD cards.
OMAP-MMC controller's can support maximum bus width of '8'.
when bus width is mentioned as "8" in controller data,the SD
stack will check whether bus width is "4" and if not it will
set bus width to "1" and there by degrading peformance.
This patch fixes the issue and improves the performance of
SD cards.

Signed-off-by: Kishore Kadiyala <[email protected]>
---
Here are my experiment numbers, on a Class 6 SDHC card:
Read peformance is increased by 220%
Write Performance is increased by 52%

drivers/mmc/host/omap_hsmmc.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 83f0aff..8c97c22 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -2092,7 +2092,7 @@ static int __init omap_hsmmc_probe(struct platform_device
*pdev)
MMC_CAP_WAIT_WHILE_BUSY;

if (mmc_slot(host).wires >= 8)
- mmc->caps |= MMC_CAP_8_BIT_DATA;
+ mmc->caps |= (MMC_CAP_8_BIT_DATA | MMC_CAP_4_BIT_DATA);
else if (mmc_slot(host).wires >= 4)
mmc->caps |= MMC_CAP_4_BIT_DATA;

--
1.6.3.3

---

Attachments:

0001-Fix-for-bus-width-which-optimizes-SD-card-s-peforman.patch (1.36 kB)

2010-02-11 17:34:36

by Madhusudhan

[permalink] [raw]

Subject: RE: [PATCH] OMAP: Fix for bus width which improves SD card's peformance.

---

> -----Original Message-----
> From: kishore kadiyala [mailto:[email protected]]
> Sent: Thursday, February 11, 2010 8:20 AM
> To: [email protected]; [email protected]
> Cc: [email protected]; [email protected]
> Subject: [PATCH] OMAP: Fix for bus width which improves SD card's
> peformance.
>
> This patch improves low speeds for SD cards.
> OMAP-MMC controller's can support maximum bus width of '8'.
> when bus width is mentioned as "8" in controller data,the SD
> stack will check whether bus width is "4" and if not it will
> set bus width to "1" and there by degrading peformance.
> This patch fixes the issue and improves the performance of
> SD cards.
>
> Signed-off-by: Kishore Kadiyala <[email protected]>

ACK

Acked-by: Madhusudhan Chikkature <[email protected]>

> ---
> Here are my experiment numbers, on a Class 6 SDHC card:
> Read peformance is increased by 220%
> Write Performance is increased by 52%
>
> drivers/mmc/host/omap_hsmmc.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 83f0aff..8c97c22 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -2092,7 +2092,7 @@ static int __init omap_hsmmc_probe(struct
> platform_device
> *pdev)
> MMC_CAP_WAIT_WHILE_BUSY;
>
> if (mmc_slot(host).wires >= 8)
> - mmc->caps |= MMC_CAP_8_BIT_DATA;
> + mmc->caps |= (MMC_CAP_8_BIT_DATA | MMC_CAP_4_BIT_DATA);
> else if (mmc_slot(host).wires >= 4)
> mmc->caps |= MMC_CAP_4_BIT_DATA;
>
> --
> 1.6.3.3