get problem while implementing EBI's SRAM.

[shownb]

Has anyone tested the code in ebi.c? The line

ioctl(fd, EBI_IOC_SPEED, &ebi);

seems to be ineffective, which makes me doubt if the driver is usable. because https://github.com/OpenNuvoton/MA35D1_linux-5.10.y/blob/896b79e89a81adfc28bae91759f53cca18b8edd8/drivers/misc/ma35d1-ebi.c#L101

I'm facing an issue where when I run

*(char *)(pEbiBuffer+i)=(char)85;

if i is an Even number, writing (char)85 and then reading it back gives me (char)84.

here is my code

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <asm/ioctl.h>
#include <sys/mman.h>
#include "nua3500-ebi.h"

#define __CH        (0)//0~2

int main(int argc, char **argv)
{
    int fd,i,j;
    unsigned char *pEbiBuffer;
    unsigned long uEbiSize;
    unsigned int patterns[4]= {0x00000000,0x55555555,0xAAAAAAAA,0xFFFFFFFF};
    unsigned char *patternsSwaps[4] = {NULL, NULL, NULL, NULL};
    struct nua3500_set_ebi ebi;
    char dev[3][14] = {"/dev/ebi0",
            "/dev/ebi1",
            "/dev/ebi2"
            };

    if (sizeof(int) != 4) {
        printf("sizeof(int) != 4\n");
        exit(0);
    }

    i = __CH;
    fd = open(&dev[i][0], O_RDWR);
    if(fd < 0)
        printf("Open ebi%d error !!!\n", i);

    ebi.bank = i;
    ebi.base = 0x68000000 + (i * 0x100000);
    printf("EBI Bank %d Addr: 0x%08x\n", ebi.bank, ebi.base);

    ebi.busmode = EBI_OPMODE_ADSEPARATE;
    ebi.CSActiveLevel = EBI_CS_ACTIVE_LOW;
    ebi.width = EBI_BUSWIDTH_16BIT;

    //ioctl(fd, EBI_IOC_SET, &ebi);
    if (ioctl(fd, EBI_IOC_SET, &ebi) == -1) {
        printf("set errno %d\n", errno);
        close(fd);
        exit(EXIT_FAILURE);
    }

    //ioctl(fd, EBI_IOC_SPEED, &ebi);

    if (ioctl(fd, EBI_IOC_SPEED, &ebi) == -1) {
    printf("speed errno %d\n", errno);
        //close(fd);
        //exit(EXIT_FAILURE);
    }

    uEbiSize = 0x100000;
    printf("EbiSize: 0x%08x\n", uEbiSize);
    if (uEbiSize % 4) {
        printf("uEbiSize is not 4 bytes aligned\n");
        exit(0);
    }
    pEbiBuffer = mmap(NULL, uEbiSize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
    if (pEbiBuffer == MAP_FAILED) {
        printf("mmap() failed\n");
        exit(0);
    }

    printf("Start to Word Read/Write test\n");
    char tmp;
    for(i = 0; i < 20; i++) {
        *(char *)(pEbiBuffer+i)=(char)85;
        tmp=*(char *)(pEbiBuffer+i);
        printf("patterns=0x%08x, data[%d]=0x%08x\n",(char)85,i,*(char*)(pEbiBuffer+i));
    }

    close(fd);
    munmap(pEbiBuffer, uEbiSize);

    return 0;
}

result:

[root@ma35d1]~# ./ebi_demo
EBI Bank 0 Addr: 0x68000000
speed errno 25
EbiSize: 0x00100000
Start to Word Read/Write test
patterns=0x00000055, data[0]=0x00000054
patterns=0x00000055, data[1]=0x00000055
patterns=0x00000055, data[2]=0x00000054
patterns=0x00000055, data[3]=0x00000055
patterns=0x00000055, data[4]=0x00000054
patterns=0x00000055, data[5]=0x00000055
patterns=0x00000055, data[6]=0x00000054
patterns=0x00000055, data[7]=0x00000055
patterns=0x00000055, data[8]=0x00000054
patterns=0x00000055, data[9]=0x00000055
patterns=0x00000055, data[10]=0x00000054
patterns=0x00000055, data[11]=0x00000055
patterns=0x00000055, data[12]=0x00000054
patterns=0x00000055, data[13]=0x00000055
patterns=0x00000055, data[14]=0x00000054
patterns=0x00000055, data[15]=0x00000055
patterns=0x00000055, data[16]=0x00000054
patterns=0x00000055, data[17]=0x00000055
patterns=0x00000055, data[18]=0x00000054
patterns=0x00000055, data[19]=0x00000055

any idea is very welcome.

[ychuang3]

The EBI data width is 16-bits. Please use (unsigned short ) instead of (char )

[shownb]

The EBI data width is 16-bits. Please use (unsigned short ) instead of (char )

Thank you very much for your response. In fact, I tried the code provided in the example as my first attempt.

[root@ma35d1]~# ./ebi_demo
EBI Bank 0 Addr: 0x68000000
EbiSize: 0x00100000
Start to Word Read/Write test
Read/Write test failed, patterns=0x55555555, data[0]=0x55545554

I have also tried many other possibilities, but things didn't go as expected. I'm really at a loss, so I thought I'd ask if you have any inspiration.

[ychuang3]

The sample program seems not correct. It used 32-biits read/write. Please try use (short ) instead of (int ). And use 16-bits test pattern 0x5555.

[shownb]

The sample program seems not correct. It used 32-biits read/write. Please try use (short ) instead of (int ). And use 16-bits test pattern 0x5555.

it does not work. any more idea?

unsigned short patterns[4]= {0x5555,0x0000,0xFFFF,0xAAAA};
/*
skip not import code
*/
    printf("Start to Word Read/Write with short 0.001\n");
    for(i=0; i<uEbiSize; i+=4) {
        unsigned short tmp;
        for(j=0; j<4; j++) {
            *(unsigned short *)(pEbiBuffer+i)=patterns[j];
            tmp=*(unsigned short *)(pEbiBuffer+i);
            printf("Read/Write test failed, patterns=0x%04x, data[%d]=0x%04x\n",patterns[j],i,*(unsigned short*)(pEbiBuffer+i));
            if(tmp!=patterns[j]) {
                printf("Read/Write test failed, patterns=0x%04x, data[%d]=0x%04x\n",patterns[j],i,*(unsigned short*)(pEbiBuffer+i));
                return 0;
            }
        }
    }

[root@ma35d1]~# ./ebi_demo EBI Bank 0 Addr: 0x68000000 EbiSize: 0x00100000 Start to Word Read/Write with short 0.001 Read/Write test failed, patterns=0x5555, data[0]=0x5554 Read/Write test failed, patterns=0x5555, data[0]=0x5554

I would like to ask, 1 What was the hardware environment in your test code? What model of SRAM was being used? 2 which busmode was being used?

[ychuang3]

How about other test patterns? 0x0000, 0xFFFF, 0xAAAA ... Can you get the waveform by a scope? Or, you can try to adjust the EBI timing by modify device tree .dts file.

[shownb]

How about other test patterns? 0x0000, 0xFFFF, 0xAAAA ... Can you get the waveform by a scope? Or, you can try to adjust the EBI timing by modify device tree .dts file.

unsigned short patterns[4]= {0x5555,0x7777,0xbbbb,0xffff};
//skip not import code
    printf("Start to Word Read/Write with short 0.002\n");
    for(i=0; i<5; i+=2) {
        short tmp;
        for(j=0; j<4; j++) {
            *(unsigned short *)(pEbiBuffer+i)=patterns[j];
            tmp=*(unsigned short *)(pEbiBuffer+i);
            printf("Read/Write, write=0x%04x, read=0x%04x\n",patterns[j],*(unsigned short*)(pEbiBuffer+i));
        }
    }

output

[root@ma35d1]~# ./ebi_demo
EBI Bank 0 Addr: 0x68000000
EbiSize: 0x00100000
Start to Word Read/Write with short 0.002
Read/Write, write=0x5555, read=0x5554
Read/Write, write=0x7777, read=0x7776
Read/Write, write=0xbbbb, read=0xbbba
Read/Write, write=0xffff, read=0xfffe
Read/Write, write=0x5555, read=0x5554
Read/Write, write=0x7777, read=0x7776
Read/Write, write=0xbbbb, read=0xbbba
Read/Write, write=0xffff, read=0xfffe
Read/Write, write=0x5555, read=0x5554
Read/Write, write=0x7777, read=0x7776
Read/Write, write=0xbbbb, read=0xbbba
Read/Write, write=0xffff, read=0xfffe
Compare data passed

and i found that if Even number at Even address,it will got problem.

i will try to ad the ebi timing,and how to do that?

        MCLKDIV = <2>;//0 ~ 7,EBI_CTL0[10:8]
        tALE = <1>;//0 ~ 7,EBI_CTL0[18:16]
        tACC = <1>;//0 ~ 31, EBI_TCTLx[7:3]
        tAHD = <1>;//0 ~ 7, EBI_TCTLx[10:9]
        IDLE  = <3>;//0 ~ 15, EBI_TCTLx[27:24] and EBI_TCTLx[15:12]

[ychuang3]

The data bit 0 is consistently 0 in all test cases. Please check if there is any cold welding issue with the pin.

MCLKDIV represents the EBI clock divider. A value of 2 indicates that it is divided by 4 from the HCLK. MCLKDIV values 0, 1, 2, 3, 4... correspond to division factors of 1, 2, 4, 8, ...

For other timings, a higher value indicates a longer delay.

[shownb]

Finally found the reason, because of pin. thank you very much for your help.

[shownb]

By the way, I have a question. I'm using IS62WV51216BLL SRAM, which has a high-speed access time: 45ns , 55ns. In other words, the theoretical speed can reach 36M/s. However, when I tested it with the following code, I found that it couldn't reach the theoretical value. What could be the reason for this?

    // begin
    struct timespec time_start = { 0, 0 }, time_end = { 0, 0 };
    clock_gettime(CLOCK_REALTIME, &time_start);
    *(unsigned short *)pEbiBuffer = pattern;
    clock_gettime(CLOCK_REALTIME, &time_end);
    printf("Elapsed Time::%lds %ldns\n", time_end.tv_sec-time_start.tv_sec,
           time_end.tv_nsec-time_start.tv_nsec);

Elapsed Time: 0s 4334ns

[ychuang3]

The current setting of EBI MCLK is HCLK divided by 4, which means it is running at 150MHz / 4. You can try modifying the device tree's MCLKDIV setting to either <0> or <1>. These values correspond to dividing by 1 and 2, respectively. The MCLK value determines the speed of the EBI. In addition, for performance testing, it is recommended to perform mass data access and calculate the average performance.

[shownb]

the default MCLK is: MCLKDIV = <2>; I changed the vaule like that: MCLKDIV = <0>; But looks like not too much Improve.

Can you tell me how fast you can reach? Do I still have an optimized place? For example, SRAM choices

[ychuang3]

Did you modify your performance measurement code? It seems to have some issues. Invoking clock_gettime() itself cosume much more time than the EBI read command. It's recommend to have a loop, for example

clock_gettime(CLOCK_REALTIME, &time_start); for (i = 0; i < 100000; i++) (unsigned short )pEbiBuffer = pattern; clock_gettime(CLOCK_REALTIME, &time_end); printf("Elapsed Time::%lds %ldns\n", time_end.tv_sec-time_start.tv_sec, time_end.tv_nsec-time_start.tv_nsec);

And get the average time. Or, use a scope to meaure it.

[ychuang3]

Additionally, may I ask for what purpose are you using EBI to interface with SRAM? What application does your product serve? Furthermore, may I inquire through which channel did you obtain the MA35D1 development board? Are you using an SOM or an IoT board?

[shownb]

MCLKDIV = <0>

MCLKDIV = <0> There will be random inconsistencies between what is written and what is read. MCLKDIV = <1> is ok.

My purpose of using ma35 is to develop a smart agriculture project. I got my SOM from taobao.

Thanks for your help, I'm going to close this issue.