[U-Boot] [PATCH v3] OMAP3 MMC: Fix warning dereferencing type-punned pointer

[Tom]

Dirk Behme wrote:
> Fix warning
> 
> dereferencing type-punned pointer will break strict-aliasing rules
> 
> Signed-off-by: Dirk Behme <dirk.behme at googlemail.com>
> CC: Steve Sakoman <sakoman at gmail.com>
> CC: Tom Rix <Tom.Rix at windriver.com>
> 
> ---
> 
> Changes in v3: Move union type definition to architecture mmc.h as proposed
> by Tom.
> 
> Changes in v2: Union elements mmc_resp_r3 and mmc_resp_r6 are no pointers.
> v1 of this patch breaks MMC handling. Please revert v1 in u-boot-ti 
> 
> http://git.denx.de/?p=u-boot/u-boot-ti.git;a=commit;h=eb19df366587c887a406d1816fa7f7dca07f537d
> 
> and use this one. Thanks to Steve Sakoman for reporting this!
> 
> Compile and boot tested on BeagleBoard.

Ack-ed

Tom



> 
>  drivers/mmc/omap3_mmc.c          |   48 +++++++++++++++++----------------------
>  include/asm-arm/arch-omap3/mmc.h |    7 +++++
>  2 files changed, 28 insertions(+), 27 deletions(-)
> 
> Index: u-boot-ti/drivers/mmc/omap3_mmc.c
> ===================================================================
> --- u-boot-ti.orig/drivers/mmc/omap3_mmc.c
> +++ u-boot-ti/drivers/mmc/omap3_mmc.c
> @@ -235,8 +235,8 @@ unsigned char mmc_detect_card(mmc_card_d
>  	unsigned char err;
>  	unsigned int argument = 0;
>  	unsigned int ocr_value, ocr_recvd, ret_cmd41, hcs_val;
> -	unsigned int resp[4];
>  	unsigned short retry_cnt = 2000;
> +	mmc_resp_t mmc_resp;
>  
>  	/* Set to Initialization Clock */
>  	err = mmc_clock_config(CLK_400KHZ, 0);
> @@ -247,18 +247,18 @@ unsigned char mmc_detect_card(mmc_card_d
>  	argument = 0x00000000;
>  
>  	ocr_value = (0x1FF << 15);
> -	err = mmc_send_cmd(MMC_CMD0, argument, resp);
> +	err = mmc_send_cmd(MMC_CMD0, argument, mmc_resp.resp);
>  	if (err != 1)
>  		return err;
>  
>  	argument = SD_CMD8_CHECK_PATTERN | SD_CMD8_2_7_3_6_V_RANGE;
> -	err = mmc_send_cmd(MMC_SDCMD8, argument, resp);
> +	err = mmc_send_cmd(MMC_SDCMD8, argument, mmc_resp.resp);
>  	hcs_val = (err == 1) ?
>  		MMC_OCR_REG_HOST_CAPACITY_SUPPORT_SECTOR :
>  		MMC_OCR_REG_HOST_CAPACITY_SUPPORT_BYTE;
>  
>  	argument = 0x0000 << 16;
> -	err = mmc_send_cmd(MMC_CMD55, argument, resp);
> +	err = mmc_send_cmd(MMC_CMD55, argument, mmc_resp.resp);
>  	if (err == 1) {
>  		mmc_card_cur->card_type = SD_CARD;
>  		ocr_value |= hcs_val;
> @@ -272,24 +272,24 @@ unsigned char mmc_detect_card(mmc_card_d
>  	}
>  
>  	argument = ocr_value;
> -	err = mmc_send_cmd(ret_cmd41, argument, resp);
> +	err = mmc_send_cmd(ret_cmd41, argument, mmc_resp.resp);
>  	if (err != 1)
>  		return err;
>  
> -	ocr_recvd = ((mmc_resp_r3 *) resp)->ocr;
> +	ocr_recvd = mmc_resp.r3.ocr;
>  
>  	while (!(ocr_recvd & (0x1 << 31)) && (retry_cnt > 0)) {
>  		retry_cnt--;
>  		if (mmc_card_cur->card_type == SD_CARD) {
>  			argument = 0x0000 << 16;
> -			err = mmc_send_cmd(MMC_CMD55, argument, resp);
> +			err = mmc_send_cmd(MMC_CMD55, argument, mmc_resp.resp);
>  		}
>  
>  		argument = ocr_value;
> -		err = mmc_send_cmd(ret_cmd41, argument, resp);
> +		err = mmc_send_cmd(ret_cmd41, argument, mmc_resp.resp);
>  		if (err != 1)
>  			return err;
> -		ocr_recvd = ((mmc_resp_r3 *) resp)->ocr;
> +		ocr_recvd = mmc_resp.r3.ocr;
>  	}
>  
>  	if (!(ocr_recvd & (0x1 << 31)))
> @@ -318,22 +318,22 @@ unsigned char mmc_detect_card(mmc_card_d
>  	if (!(ocr_recvd & ocr_value))
>  		return 0;
>  
> -	err = mmc_send_cmd(MMC_CMD2, argument, resp);
> +	err = mmc_send_cmd(MMC_CMD2, argument, mmc_resp.resp);
>  	if (err != 1)
>  		return err;
>  
>  	if (mmc_card_cur->card_type == MMC_CARD) {
>  		argument = mmc_card_cur->RCA << 16;
> -		err = mmc_send_cmd(MMC_CMD3, argument, resp);
> +		err = mmc_send_cmd(MMC_CMD3, argument, mmc_resp.resp);
>  		if (err != 1)
>  			return err;
>  	} else {
>  		argument = 0x00000000;
> -		err = mmc_send_cmd(MMC_SDCMD3, argument, resp);
> +		err = mmc_send_cmd(MMC_SDCMD3, argument, mmc_resp.resp);
>  		if (err != 1)
>  			return err;
>  
> -		mmc_card_cur->RCA = ((mmc_resp_r6 *) resp)->newpublishedrca;
> +		mmc_card_cur->RCA = mmc_resp.r6.newpublishedrca;
>  	}
>  
>  	writel(readl(&mmc_base->con) & ~OD, &mmc_base->con);
> @@ -437,10 +437,9 @@ unsigned char configure_mmc(mmc_card_dat
>  {
>  	unsigned char ret_val;
>  	unsigned int argument;
> -	unsigned int resp[4];
>  	unsigned int trans_clk, trans_fact, trans_unit, retries = 2;
> -	mmc_csd_reg_t Card_CSD;
>  	unsigned char trans_speed;
> +	mmc_resp_t mmc_resp;
>  
>  	ret_val = mmc_init_setup();
>  
> @@ -453,21 +452,16 @@ unsigned char configure_mmc(mmc_card_dat
>  	} while ((retries > 0) && (ret_val != 1));
>  
>  	argument = mmc_card_cur->RCA << 16;
> -	ret_val = mmc_send_cmd(MMC_CMD9, argument, resp);
> +	ret_val = mmc_send_cmd(MMC_CMD9, argument, mmc_resp.resp);
>  	if (ret_val != 1)
>  		return ret_val;
>  
> -	((unsigned int *) &Card_CSD)[3] = resp[3];
> -	((unsigned int *) &Card_CSD)[2] = resp[2];
> -	((unsigned int *) &Card_CSD)[1] = resp[1];
> -	((unsigned int *) &Card_CSD)[0] = resp[0];
> -
>  	if (mmc_card_cur->card_type == MMC_CARD)
> -		mmc_card_cur->version = Card_CSD.spec_vers;
> +		mmc_card_cur->version = mmc_resp.Card_CSD.spec_vers;
>  
> -	trans_speed = Card_CSD.tran_speed;
> +	trans_speed = mmc_resp.Card_CSD.tran_speed;
>  
> -	ret_val = mmc_send_cmd(MMC_CMD4, MMC_DSR_DEFAULT << 16, resp);
> +	ret_val = mmc_send_cmd(MMC_CMD4, MMC_DSR_DEFAULT << 16, mmc_resp.resp);
>  	if (ret_val != 1)
>  		return ret_val;
>  
> @@ -491,18 +485,18 @@ unsigned char configure_mmc(mmc_card_dat
>  		return ret_val;
>  
>  	argument = mmc_card_cur->RCA << 16;
> -	ret_val = mmc_send_cmd(MMC_CMD7_SELECT, argument, resp);
> +	ret_val = mmc_send_cmd(MMC_CMD7_SELECT, argument, mmc_resp.resp);
>  	if (ret_val != 1)
>  		return ret_val;
>  
>  	/* Configure the block length to 512 bytes */
>  	argument = MMCSD_SECTOR_SIZE;
> -	ret_val = mmc_send_cmd(MMC_CMD16, argument, resp);
> +	ret_val = mmc_send_cmd(MMC_CMD16, argument, mmc_resp.resp);
>  	if (ret_val != 1)
>  		return ret_val;
>  
>  	/* get the card size in sectors */
> -	ret_val = mmc_read_cardsize(mmc_card_cur, &Card_CSD);
> +	ret_val = mmc_read_cardsize(mmc_card_cur, &mmc_resp.Card_CSD);
>  	if (ret_val != 1)
>  		return ret_val;
>  
> Index: u-boot-ti/include/asm-arm/arch-omap3/mmc.h
> ===================================================================
> --- u-boot-ti.orig/include/asm-arm/arch-omap3/mmc.h
> +++ u-boot-ti/include/asm-arm/arch-omap3/mmc.h
> @@ -223,6 +223,13 @@ typedef struct {
>  	unsigned short newpublishedrca;
>  } mmc_resp_r6;
>  
> +typedef union {
> +	unsigned int resp[4];
> +	mmc_resp_r3 r3;
> +	mmc_resp_r6 r6;
> +	mmc_csd_reg_t Card_CSD;
> +} mmc_resp_t;
> +
>  extern mmc_card_data mmc_dev;
>  
>  unsigned char mmc_lowlevel_init(void);