Re: [PATCH] Samsung S3C24xx SD/MMC driver

From: Pierre Ossman
Date: Wed Dec 19 2007 - 11:54:51 EST

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On Wed, 19 Dec 2007 15:22:13 +0100
Harald Welte <laforge@xxxxxxxxxxxx> wrote:

> Hi!
>
> This is a MMC/SD driver for the Samsung S3C24xx SD/MMC controller, originally
> developed years ago by Thomas Kleffel <tk@xxxxxxxxxxx>.
>
> Due to time constraints, he had no time to further maintain the driver
> and follow the mainline Linux changes in the SD/MMC stack.
>
> With his authorization, I have taken over the task of making it
> compliant to the current mainline SD/MMC API and take care of the
> mainline kernel merge.
>
> So please advise on whatever changes you deem neccessary and I'll try to
> do my best to incorporate them for a hopefully not-too-distant mainline
> merge.
>
> After a potential kernel inclusion, we would co-maintain the driver.
>
> Acked-by: Thomas Kleffel <tk@xxxxxxxxxxx>
> Signed-off-by: Harald Welte <laforge@xxxxxxxxxxxx>
>
> ---

Well, my biggest beef with this driver is the excessive debug code. I did a cleanup in an older version of the driver, but it shouldn't be to difficult to do the same for this one. I've included my patch for reference.

> Index: linux-2.6/drivers/mmc/host/s3cmci.c
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/mmc/host/s3cmci.c

> +#include <linux/mmc/mmc.h>

This is always a warning sign. It should never be needed in a host driver.

> +
> +static inline int get_data_buffer(struct s3cmci_host *host,
> + u32 *words, u32 **pointer)
> +{
> + struct scatterlist *sg;
> +
> + if (host->pio_active == XFER_NONE)
> + return -EINVAL;
> +
> + if ((!host->mrq) || (!host->mrq->data))
> + return -EINVAL;
> +
> + if (host->pio_sgptr >= host->mrq->data->sg_len) {
> + dbg(host, dbg_debug, "no more buffers (%i/%i)\n",
> + host->pio_sgptr, host->mrq->data->sg_len);
> + return -EBUSY;
> + }
> + sg = &host->mrq->data->sg[host->pio_sgptr];
> +
> + *words = sg->length >> 2;
> + *pointer = page_address(sg_page(sg)) + sg->offset;
> +

The length might not be a multiple of four. And it might also be completely unaligned. Make sure you can either handle such requests, or fail them with -EINVAL.

Rgds
--
-- Pierre Ossman

Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org
commit 4e47c91b7ca45940af384d3c9919a0eb160a2fb9
Author: Pierre Ossman <drzeus@xxxxxxxxx>
Date: Fri Jun 1 08:19:15 2007 +0200

s3mci: remove extra debug info

Remove excessive and unmaintained debug strings. This kind of debug
info should also be in the MMC layer, not drivers.

Signed-off-by: Pierre Ossman <drzeus@xxxxxxxxx>

diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
index 7c2eb45..42fa90f 100644
--- a/drivers/mmc/Makefile
+++ b/drivers/mmc/Makefile
@@ -30,6 +30,5 @@ mmc_core-y := mmc.o mmc_sysfs.o
mmc_core-$(CONFIG_BLOCK) += mmc_queue.o

ifeq ($(CONFIG_MMC_DEBUG),y)
-obj-$(CONFIG_MMC) += mmc_debug.o
EXTRA_CFLAGS += -DDEBUG
endif
diff --git a/drivers/mmc/mmc_debug.c b/drivers/mmc/mmc_debug.c
deleted file mode 100644
index f13e223..0000000
--- a/drivers/mmc/mmc_debug.c
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * linux/drivers/mmc/mmc_debug.c
- *
- * Copyright (C) 2003 maintech GmbH, Thomas Kleffel <tk@xxxxxxxxxxx>
- *
- * This file contains debug helper functions for the MMC/SD stack
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- */
-
-#include <linux/mmc/mmc.h>
-#include "mmc_debug.h"
-
-char *mmc_cmd2str(int cmd)
-{
- switch(cmd) {
- case 0: return "GO_IDLE_STATE";
- case 1: return "ALL_SEND_OCR";
- case 2: return "ALL_SEND_CID";
- case 3: return "ALL_SEND_RELATIVE_ADD";
- case 6: return "ACMD: SD_SET_BUSWIDTH";
- case 7: return "SEL_DESEL_CARD";
- case 9: return "SEND_CSD";
- case 10: return "SEND_CID";
- case 11: return "READ_UNTIL_STOP";
- case 12: return "STOP_TRANSMISSION";
- case 13: return "SEND_STATUS";
- case 15: return "GO_INACTIVE_STATE";
- case 16: return "SET_BLOCKLEN";
- case 17: return "READ_SINGLE_BLOCK";
- case 18: return "READ_MULTIPLE_BLOCK";
- case 24: return "WRITE_SINGLE_BLOCK";
- case 25: return "WRITE_MULTIPLE_BLOCK";
- case 41: return "ACMD: SD_APP_OP_COND";
- case 55: return "APP_CMD";
- default: return "UNKNOWN";
- }
-}
-EXPORT_SYMBOL(mmc_cmd2str);
-
-char *mmc_err2str(int err)
-{
- switch(err) {
- case MMC_ERR_NONE: return "OK";
- case MMC_ERR_TIMEOUT: return "TIMEOUT";
- case MMC_ERR_BADCRC: return "BADCRC";
- case MMC_ERR_FIFO: return "FIFO";
- case MMC_ERR_FAILED: return "FAILED";
- case MMC_ERR_INVALID: return "INVALID";
- case MMC_ERR_BUSY: return "BUSY";
- case MMC_ERR_DMA: return "DMA";
- case MMC_ERR_CANCELED: return "CANCELED";
- default: return "UNKNOWN";
- }
-}
-EXPORT_SYMBOL(mmc_err2str);
diff --git a/drivers/mmc/mmc_debug.h b/drivers/mmc/mmc_debug.h
deleted file mode 100644
index 5a84852..0000000
--- a/drivers/mmc/mmc_debug.h
+++ /dev/null
@@ -1,7 +0,0 @@
-#ifndef MMC_DEBUG_H
-#define MMC_DEBUG_H
-
-char *mmc_cmd2str(int err);
-char *mmc_err2str(int err);
-
-#endif /* MMC_DEBUG_H */
diff --git a/drivers/mmc/s3cmci.c b/drivers/mmc/s3cmci.c
index 9b15310..4069f50 100644
--- a/drivers/mmc/s3cmci.c
+++ b/drivers/mmc/s3cmci.c
@@ -24,7 +24,6 @@
#include <asm/arch/regs-gpio.h>
#include <asm/arch/mci.h>

-#include "mmc_debug.h"
#include "s3cmci.h"

#define DRIVER_NAME "s3c-mci"
@@ -106,8 +105,8 @@ static void prepare_dbgmsg(struct s3cmci_host *host, struct mmc_command *cmd,
int stop)
{
snprintf(host->dbgmsg_cmd, 300,
- "#%u%s op:%s(%i) arg:0x%08x flags:0x08%x retries:%u",
- host->ccnt, (stop?" (STOP)":""), mmc_cmd2str(cmd->opcode),
+ "#%u%s op:CMD%d arg:0x%08x flags:0x08%x retries:%u",
+ host->ccnt, (stop?" (STOP)":""),
cmd->opcode, cmd->arg, cmd->flags, cmd->retries);

if (cmd->data) {
@@ -134,20 +133,18 @@ static void dbg_dumpcmd(struct s3cmci_host *host, struct mmc_command *cmd,
dbg(host, dbglvl, "CMD[OK] %s R0:0x%08x\n",
host->dbgmsg_cmd, cmd->resp[0]);
} else {
- dbg(host, dbglvl, "CMD[%s] %s Status:%s\n",
- mmc_err2str(cmd->error), host->dbgmsg_cmd,
- host->status);
+ dbg(host, dbglvl, "CMD[FAIL(%d)] %s Status:%s\n",
+ cmd->error, host->dbgmsg_cmd, host->status);
}

if (!cmd->data)
return;

if (cmd->data->error == MMC_ERR_NONE) {
- dbg(host, dbglvl, "DAT[%s] %s\n",
- mmc_err2str(cmd->data->error), host->dbgmsg_dat);
+ dbg(host, dbglvl, "DAT[OK] %s\n", host->dbgmsg_dat);
} else {
- dbg(host, dbglvl, "DAT[%s] %s DCNT:0x%08x\n",
- mmc_err2str(cmd->data->error), host->dbgmsg_dat,
+ dbg(host, dbglvl, "DAT[FAIL(%d)] %s DCNT:0x%08x\n",
+ cmd->data->error, host->dbgmsg_dat,
readl(host->base + S3C2410_SDIDCNT));
}
}

Next message: Ingo Molnar: "Re: [PATCH] x86: Fix DMI out of memory problems"
Previous message: Lee Schermerhorn: "Re: [patch 02/20] make the inode i_mmap_lock a reader/writer lock"
In reply to: Harald Welte: "[PATCH] Samsung S3C24xx SD/MMC driver"
Next in thread: Harald Welte: "Re: [PATCH] Samsung S3C24xx SD/MMC driver"
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